Near-Field Antenna for Wireless Power Transmission with Four Coplanar Antenna Elements that Each Follows a Respective Meandering Pattern

ABSTRACT

A near-field antenna is provided, which includes: a reflector and four distinct antenna elements, offset from the reflector, each of the four distinct antenna elements following respective meandering patterns. Two antenna elements of the four antenna elements form a first dipole antenna along a first axis, and another two antenna elements of the four antenna elements form a second dipole antenna along a second axis perpendicular to the first axis. The near-field antenna further includes: (i) a power amplifier configured to feed electromagnetic signals to one of the dipole antennas, (ii) an impedance-adjusting component configured to adjust an impedance of one of the dipole antennas, and (iii) switch circuitry coupled to the power amplifier, the impedance-adjusting component, and the dipole antennas. The switch circuitry is configured to switchably couple the first dipole antenna to the power amplifier and the second dipole antenna to the impedance-adjusting component, and vice versa.

RELATED APPLICATIONS

This application is a continuation-in-part of PCT Patent Application No.PCT/US17/65886, filed Dec. 12, 2017, which is a continuation of U.S.Non-Provisional patent application Ser. No. 15/833,790, filed Dec. 6,2017, which is a continuation-in-part of U.S. Non-Provisional patentapplication Ser. No. 15/424,552, filed Feb. 3, 2017, which claimspriority to U.S. Provisional Application Ser. No. 62/433,227, filed Dec.12, 2016. PCT Patent Application No. PCT/US17/65886 also claims priorityto U.S. Provisional Application Ser. No. 62/541,581, filed Aug. 4, 2017.Each of these applications is hereby incorporated by reference in itsrespective entirety.

This application is also a continuation-in-part of U.S. Non-Provisionalpatent application Ser. No. 15/269,729, filed Sep. 19, 2016, which (i)claims priority to U.S. Provisional Application Ser. No. 62/374,578,filed Aug. 12, 2016, and (ii) is also a continuation-in-part of U.S.Non-Provisional patent application Ser. No. 15/046,348, filed Feb. 17,2016, which claims priority to U.S. Provisional Application Ser. No.62/387,205, filed Dec. 24, 2015. Each of these applications is herebyincorporated by reference in its respective entirety.

TECHNICAL FIELD

The embodiments herein generally relate to near-field wireless powertransmission systems (e.g., antennas, software, and devices used in suchsystems) and, more specifically, to a near-field antenna for wirelesspower transmission with four coplanar antenna elements that each followsa respective meandering pattern.

BACKGROUND

Conventional charging pads utilize inductive coils to generate amagnetic field that is used to charge a device. Users typically mustplace the device at a specific position on the charging pad and areunable to move the device to different positions on the pad, withoutinterrupting or terminating the charging of the device. This results ina frustrating experience for many users as they may be unable to locatethe device at the exact right position on the pad in which to startcharging their device. Often, users may think that their device has beenproperly positioned, but may then dishearteningly find hours later thatvery little (or no) energy has been transferred.

Conventional charging pads also utilize components that are distributedacross multiple different integrated circuits. Such a configurationresults in processing delays that cause these charging pads to operateslower (e.g., wireless charging and adjustments made during wirelesscharging takes longer) than is desired by users of such pads.

SUMMARY

Accordingly, there is a need for wireless charging systems (e.g., RFcharging pads) that address the problems identified above. To this end,an RF charging pad is described herein that includes components that areefficiently arranged on a single integrated circuit, and that singleintegrated circuit manages antennas of the RF charging pad byselectively or sequentially activating antenna zones (e.g., one or moreantennas or unit cell antennas of the RF charging pad that are groupedtogether, also referred to herein as an antenna group) to locate anefficient antenna zone to use for transmission of wireless power to areceiver device that is located on a surface of the RF charging pad.Such systems and methods of use thereof help to eliminate userdissatisfaction with conventional charging pads. For example, bymonitoring transferred energy while selectively activating the antennazones, such systems and methods of use thereof help to eliminate wastedRF power transmissions by ensuring that energy transfer is maximized atany point in time and at any position at which a device may be placed onan RF charging pad, thus eliminating wasteful transmissions that may notbe efficiently received.

In the description that follows, references are made to an RF chargingpad that includes various antenna zones. For the purposes of thisdescription, antenna zones include one or more transmitting antennas ofthe RF charging pad, and each antenna zone may be individuallyaddressable by a controlling integrated circuit (e.g., RF powertransmitter integrated circuit 160, FIGS. 1A-1B) to allow for selectiveactivation of each antenna zone in order to determine which antenna zoneis able to most efficiently transfer wireless power to a receiver. TheRF charging pad is also inter-changeably referred to herein as anear-field charging pad, or, more simply, as a charging pad.

(A1) In some embodiments, a method is performed at a near-field chargingpad that includes a wireless communication component (e.g.,communication component 204, FIG. 1A), a plurality of antenna zones thateach respectively include at least one antenna element (e.g., exampleantenna zones are shown in FIG. 1B), and one or more processors (e.g.,CPU 202, FIGS. 1B and 2A). The method includes detecting, via thewireless communication component, that a wireless power receiver iswithin a threshold distance of the near-field charging pad and inresponse to detecting that the wireless power receiver is within thethreshold distance of the near-field charging pad, determining whetherthe wireless power receiver has been placed on the near-field chargingpad. The method further includes, in accordance with determining thatthe wireless power receiver has been placed on the near-field chargingpad, selectively transmitting, by respective antenna elements includedin the plurality of antenna zones, respective test power transmissionsignals with a first set of transmission characteristics until adetermination is made that a particular power-delivery parameterassociated with transmission of a respective test power transmissionsignal by at least one particular antenna zone of the plurality ofantenna zones satisfies power-delivery criteria. Upon determining, bythe one or more processors, that the particular power-delivery parametersatisfies the power-delivery criteria, the method further includestransmitting a plurality of additional power transmission signals to thewireless power receiver using the at least one particular antenna zone,wherein each additional power transmission signal of the plurality istransmitted with a second set of transmission characteristics, distinctfrom the first set.

(A2) In some embodiments of the method of A1, determining whether thewireless power receiver has been placed on the surface of the near-fieldcharging pad includes: (i) transmitting the test power transmissionsignals using each of the plurality of antenna zones, (ii) monitoring anamount of reflected power at the near-field charging pad whiletransmitting the test power transmission signals, and (iii) determiningthat the wireless power receiver has been placed on the near-fieldcharging pad when the amount of reflected power satisfies a devicedetection threshold.

(A3) In some embodiments of the method of A2, the amount of reflectedpower is measured at each antenna zone of the plurality of antennazones.

(A4) In some embodiments of the method of any of A2-A3, the devicedetection threshold is established during a calibration process for thenear-field charging pad.

(A5) In some embodiments of the method of A4, the device detectionthreshold is specific to a type of device that is coupled with thewireless power receiver, and the device detection threshold is selectedby the one or more processors after detecting the wireless powerreceiver in proximity to the near-field charging pad (e.g., the wirelesspower receiver sends a packet of information to the near-field chargingpad, and that packet of information includes information that identifiesthe type of device that is coupled with the wireless power receiver).

(A6) In some embodiments of the method of any of A1-A5, selectivelytransmitting the respective test power transmission signals is performedusing each antenna zone of the plurality of antenna zones. In addition,the method further comprises, before the determination is made that thepower-delivery parameter associated with transmission of the respectivetest power transmission signal by the at least one particular antennazone of the plurality of antenna zones satisfies the power-deliverycriteria: (i) updating a respective power-delivery parameter associatedwith transmission of a respective test power transmission signal by eachrespective antenna zone based on the transmission by each antenna zone,and (ii) selecting two or more antenna zones, including the at least oneparticular antenna zone, based on their associated respectivepower-delivery parameters, to transmit wireless power to the wirelesspower receiver.

(A7) In some embodiments of the method of A6, the method furthercomprises using each of the two or more antenna zones to transmitadditional test power transmission signals having the first set oftransmission characteristics. Moreover, the determination that theparticular power-delivery parameter satisfies the power-deliverycriteria includes determining that the particular power-deliveryparameter indicates that the particular antenna zone is more efficientlytransmitting wireless power to the wireless power receiver as comparedto other antenna zones of the two or more antenna zones.

(A8) In some embodiments of the method of any of A6-A7, thedetermination that the particular power-delivery parameter satisfies thepower-delivery criteria also includes determining that the particularpower-delivery parameter indicates that a first threshold amount ofpower is transferred to the wireless power receiver by the at least oneparticular antenna zone, and the at least one particular antenna zone isthe only antenna zone of the two or more antenna zones having arespective power-delivery parameter that indicates that the firstthreshold amount of power is transferred to the wireless power receiver.

(A9) In some embodiments of the method of any of A6-A8, thedetermination that the particular power-delivery parameter satisfies thepower-delivery criteria also includes determining that (i) no antennazone is transferring a first threshold amount of power to the wirelesspower receiver and (ii) an additional power-delivery parameterassociated with an additional antenna zone of the two or more antennazones satisfies the power-delivery criteria. In addition, the particularpower-delivery parameter indicates that a first amount of powertransferred to the wireless power receiver by the particular antennazone is above a second threshold amount of power and below the firstthreshold amount of power, and the additional power-delivery parameterindicates that a second amount of power transferred to the wirelesspower receiver by the additional antenna zone is above the secondthreshold amount of power and below the first threshold amount of power.

(A10) In some embodiments of the method of A9, both of the particularantenna group and the additional antenna group are used tosimultaneously transmit the additional plurality of power transmissionsignals to provide power to the wireless power receiver.

(A11) In some embodiments of the method of any of A1-A10, informationused to determine the power-delivery parameter is provided to thenear-field charging pad by the wireless power receiver via the wirelesscommunication component of the near-field charging pad.

(A12) In some embodiments of the method of any of A1-A11, the second setof transmission characteristics is determined by adjusting at least onecharacteristic in the first set of transmission characteristics toincrease an amount of power that is transferred by the particularantenna group to the wireless power receiver.

(A13) In some embodiments of the method of A12, the at least oneadjusted characteristic is a frequency or impedance value.

(A14) In some embodiments of the method of any of A1-A13, whiletransmitting the additional plurality of power transmission signals,adjusting at least one characteristic in the second set of transmissioncharacteristics based on information, received from the wireless powerreceiver, that is used to determine a level of power that is wirelesslydelivered to the wireless power receiver by the near-field charging pad.

(A15) In some embodiments of the method of any of A1-A14, the one ormore processors are components of a single integrated circuit that isused to control operation of the near-field charging pad. For example,any of the methods described herein are managed by the single integratedcircuit, such as an instance of the radio frequency (RF) powertransmitter integrated circuit 160 shown in FIG. 1B.

(A16) In some embodiments of the method of any of A1-A15, eachrespective power-delivery metric corresponds to an amount of powerreceived by the wireless power receiver based on transmission of arespective test power transmission signal by a respective antenna groupof the plurality of antenna groups.

(A17) In some embodiments of the method of any of A1-A16, the methodfurther includes, before transmitting the test power transmissionsignals, determining that the wireless power receiver is authorized toreceive wirelessly delivered power from the near-field charging pad.

(A18) In another aspect, a near-field charging pad is provided. In someembodiments, the near-field charging pad includes a wirelesscommunication component, a plurality of antenna zones that eachrespectively include at least one antenna element, one or moreprocessors, and memory storing one or more programs, which when executedby the one or more processors cause the near-field charging pad toperform the method described in any one of A1-A17.

(A19) In yet another aspect, a near-field charging pad is provided andthe near-field charging includes means for performing the methoddescribed in any one of A1-A17.

(A20) In still another aspect, a non-transitory computer-readablestorage medium is provided. The non-transitory computer-readable storagemedium stores executable instructions that, when executed by anear-field charging pad (that includes a wireless communicationcomponent, a plurality of antenna zones that each respectively includeat least one antenna element) with one or more processors/cores, causethe near-field charging pad to perform the method described in any oneof A1-A17.

As described above, there is also a need for an integrated circuit thatincludes components for managing transmission of wireless power that areall integrated on a single integrated circuit. Such a integrated circuitand methods of use thereof help to eliminate user dissatisfaction withconventional charging pads. By including all components on a single chip(as discussed in more detail below in reference to FIGS. 1A and 1B),such integrated circuits are able to manage operations at the integratedcircuits more efficiently and quickly (and with lower latency), therebyhelping to improve user satisfaction with the charging pads that aremanaged by these integrated circuits.

(B1) In some embodiments, an integrated circuit includes: (i) aprocessing unit that is configured to control operation of theintegrated circuit, (ii) a power converter, operatively coupled to theprocessing unit, that is configured to convert an input current intoradio frequency energy, (iii) a waveform generator, operatively coupledto the processing unit, that is configured to generate a plurality ofpower transmission signals using the radio frequency energy, (iv) afirst interface that couples the integrated circuit with a plurality ofpower amplifiers that are external to the integrated circuit, and (v) asecond interface, distinct from the first interface, that couples theintegrated circuit with a wireless communication component. Theprocessing unit is also configured to: (i) receive, via the secondinterface, an indication that a wireless power receiver is withintransmission range of a near-field charging pad controlled by theintegrated circuit, and (ii) in response to receiving the indicationprovide, via the first interface, at least some of the plurality ofpower transmission signals to at least one of the plurality of poweramplifiers.

(B2) In some embodiments of the integrated circuit of B 1, theprocessing unit includes a CPU, ROM, RAM, and encryption (e.g., CPUsubsystem 170, FIG. 1B).

(B3) In some embodiments of the integrated circuit of any of B1-B2, theinput current is direct current. Alternatively, in some embodiments, theinput current is alternating current. In these embodiments, the powerconverter is a radio frequency DC-DC converter or a radio frequencyAC-AC converter, respectively.

(B4) In some embodiments of the integrated circuit of any of B1-B3, thewireless communication component is a Bluetooth or Wi-Fi radio that isconfigured to receive communication signals from a device that is placedon a surface of the near-field charging pad.

To help address the problems described above and to thereby providecharging pads that satisfy user needs, the antenna zones described abovemay include adaptive antenna elements (e.g., antenna zones 290 of the RFcharging pad 100, FIG. 1B, may each respectively include one or more ofthe antennas 120 described below in reference to FIGS. 3A-6E and 8) thatare able to adjust energy transmission characteristics (e.g., impedanceand frequency for a conductive line of a respective antenna element) sothat the charging pad is capable of charging a device that is placed atany position on the pad.

In accordance with some embodiments, the antenna zones of the radiofrequency (RF) charging pads described herein may include: one or moreantenna elements that are in communication with the one or moreprocessors for transmitting RF signals to the RF receiver of theelectronic device. In some embodiments, each respective antenna elementincludes: (i) a conductive line forming a meandered line pattern; (ii) afirst terminal at a first end of the conductive line for receivingcurrent that flows through the conductive line at a frequency controlledby the one or more processors; and (iii) a second terminal, distinctfrom the first terminal, at a second end of the conductive line, thesecond terminal coupled with a component that is controlled by the atleast one processor and allows for modifying an impedance value at thesecond terminal. In some embodiments, the at least one processor isconfigured to adaptively adjust the frequency and/or the impedance valueto optimize the amount of energy that is transferred from the one ormore antenna elements to the RF receiver of the electronic device.

There is a need for wireless charging systems (e.g., RF charging pads)that include adaptive antenna elements that are able to adjust energytransmission characteristics (e.g., impedance and frequency for aconductive line of a respective antenna element) so that the chargingpad is capable of charging a device that is placed at any position onthe pad. In some embodiments, these charging pads include one or moreprocessors that monitor energy transferred from the transmitting antennaelements (also referred to herein as RF antenna elements or antennaelements) and to a receiver of an electronic device to be charged, andthe one or more processors optimize the energy transmissioncharacteristics to maximize energy transfer at any position on thecharging pad. Some embodiments may also include a feedback loop toreport received power at the receiver to the one or more processors.

(C1) In accordance with some embodiments, a radio frequency (RF)charging pad is provided. The RF charging pad includes: at least oneprocessor for monitoring an amount of energy that is transferred fromthe RF charging pad to an RF receiver of an electronic device. The RFcharging pad also includes: one or more antenna elements that are incommunication with the one or more processors for transmitting RFsignals to the RF receiver of the electronic device. In someembodiments, each respective antenna element includes: (i) a conductiveline forming a meandered line pattern; (ii) a first terminal at a firstend of the conductive line for receiving current that flows through theconductive line at a frequency controlled by the one or more processors;and (iii) a second terminal, distinct from the first terminal, at asecond end of the conductive line, the second terminal coupled with acomponent that is controlled by the at least one processor and allowsfor modifying an impedance value at the second terminal. In someembodiments, the at least one processor is configured to adaptivelyadjust the frequency and/or the impedance value to optimize the amountof energy that is transferred from the one or more antenna elements tothe RF receiver of the electronic device.

(C2) In accordance with some embodiments, a method is also provided thatis used to charge an electronic device through radio frequency (RF)power transmission. The method includes: providing a transmittercomprising at least one RF antenna. The method also includes:transmitting, via at the least one RF antenna, one or more RF signalsand monitoring an amount of energy that is transferred via the one ormore RF signals from the at least one RF antenna to an RF receiver. Themethod additionally includes: adaptively adjusting a characteristic ofthe transmitter to optimize the amount of energy that is transferredfrom the at least one RF antenna to the RF receiver. In someembodiments, the characteristic is selected from a group consisting of(i) a frequency of the one or more RF signals, (ii) an impedance of thetransmitter, and (iii) a combination of (i) and (ii). In someembodiments, the at least one RF antenna is a part of an array of RFantennas.

(C3) In accordance with some embodiments, a radio frequency (RF)charging pad is provided. The RF charging pad includes: one or moreprocessors for monitoring an amount of energy that is transferred fromthe RF charging pad to an RF receiver of an electronic device. The RFcharging pad also includes: one or more transmitting antenna elementsthat are configured to communicate with the one or more processors fortransmitting RF signals to the RF receiver of the electronic device. Insome embodiments, each respective antenna element includes: (i) aconductive line forming a meandered line pattern; (ii) an input terminalat a first end of the conductive line for receiving current that flowsthrough the conductive line at a frequency controlled by the one or moreprocessors; and (iii) a plurality of adaptive load terminals, distinctfrom the input terminal and distinct from each other, at a plurality ofpositions of the conductive line, each respective adaptive load terminalof the plurality of adaptive load terminals coupled with a respectivecomponent that is configured to be controlled by the one or moreprocessors and is configured to allow modifying a respective impedancevalue at the respective adaptive load terminal. In some embodiments, theone or more processors are configured to adaptively adjust at least oneof the frequency and a respective impedance value at one or more of theplurality of adaptive load terminals to optimize the amount of energythat is transferred from the one or more transmitting antenna elementsto the RF receiver of the electronic device.

(C4) In accordance with some embodiments, a method is also provided thatis used to charge an electronic device through radio frequency (RF)power transmission. The method includes: providing a charging pad thatincludes a transmitter comprising one or more RF antennas. In someembodiments, each RF antenna includes: (i) a conductive line forming ameandered line pattern; (ii) an input terminal at a first end of theconductive line for receiving current that flows through the conductiveline at a frequency controlled by one or more processors; and (iii) aplurality of adaptive load terminals, distinct from the input terminaland distinct from each other, at a plurality of positions of theconductive line, each respective adaptive load terminal of the pluralityof adaptive load terminals coupled with a respective component that iscontrolled by the one or more processors and allows for modifying arespective impedance value at the respective adaptive load terminal. Themethod also includes: transmitting, via the one or more RF antennas, oneor more RF signals, and monitoring an amount of energy that istransferred via the one or more RF signals from the one or more RFantennas to an RF receiver. The method additionally includes: adaptivelyadjusting a characteristic of the transmitter using the one or moreprocessors of the transmitter to optimize the amount of energy that istransferred from the one or more RF antennas to the RF receiver. In someembodiments, the characteristic is selected from a group consisting of(i) a frequency of the one or more RF signals, (ii) an impedance of thetransmitter, and (iii) a combination of (i) and (ii). In someembodiments, the impedance of the transmitter is adaptively adjusted ata respective one or more of the plurality of adaptive load terminals ofthe one or more RF antennas using the one or more processors of thetransmitter.

(C5) In accordance with some embodiments, a non-transitorycomputer-readable storage medium is provided. The non-transitorycomputer-readable storage medium includes executable instructions that,when executed by one or more processors that are coupled with a radiofrequency (RF) charging pad that includes one or more transmittingantenna elements, cause the one or more processors to: monitor an amountof energy that is transferred from the RF charging pad to an RF receiverof an electronic device; and communication with the one or moretransmitting antenna elements for transmitting RF signals to the RFreceiver of the electronic device. In some embodiments, each respectivetransmitting antenna element includes: a conductive line forming ameandered line pattern; an input terminal at a first end of theconductive line for receiving current that flows through the conductiveline at a frequency controlled by the one or more processors; and aplurality of adaptive load terminals, distinct from the input terminaland distinct from each other, at a plurality of positions of theconductive line, each respective adaptive load terminal of the pluralityof adaptive load terminals coupled with a respective component that isconfigured to be controlled by the one or more processors and isconfigured to allow modifying a respective impedance value at eachrespective adaptive load terminal. And the one or more processorsfurther adaptively adjust at least one of the frequency and a respectiveimpedance value at one or more of the plurality of adaptive loadterminals to optimize the amount of energy that is transferred from theone or more transmitting antenna elements to the RF receiver of theelectronic device.

(C6) In some embodiments of any of C1-C5, the frequency is in a firstfrequency band, and at least one of the one or more transmitting antennaelements is configured to operate at a second frequency band based onadaptive adjustments, by the one or more processors, to respectiveimpedance values at one or more of the plurality of adaptive loadterminals of the at least one transmitting antenna element.

(C7) In some embodiments of any of C1-C6, the RF charging pad includesan input circuit that is coupled with the one or more processors and isconfigured to provide the current to the input terminal at the first endof the conductive line, wherein the one or more processors areconfigured to adaptively adjust the frequency by instructing the inputcircuit to generate the current with a new frequency that is distinctfrom the frequency.

(C8) In some embodiments of any of C1-C7, the one or more processors areconfigured to adaptively adjust the frequency by instructing the feedingelement to generate the current with a plurality of differentfrequencies that are determined using predetermined increments.

(C9) In some embodiments of any of C1-C8, a respective conductive linefor at least one of the one or more transmitting antenna elements has arespective meandered line pattern that allows the at least onetransmitting antenna element to efficiently transmit RF signals havingthe frequency and/or the new frequency, at least two adjacent segmentsof the respective conductive line having the respective meandered linepattern have different geometric dimensions relative to each other, andthe respective conductive line has a length that remains the same whenthe at least one transmitting antenna element is configured to transmitRF signals having the frequency and/or the new frequency.

(C10) In some embodiments of any of C1-C9, at least one transmittingantenna element of the one or more transmitting antenna elements has afirst segment and a second segment, the first segment including theinput terminal, and the at least one transmitting antenna element isconfigured to: operate at the frequency while the first segment is notcoupled with the second segment, and operate at the new frequency whilethe first segment is coupled with the second segment; and the one ormore processors are configured to couple the first segment with thesecond segment in conjunction with instructing the feeding element togenerate the current with the new frequency that is distinct from thefrequency.

(C11) In some embodiments of any of C1-C10, the one or more processorsare configured to: adaptively adjust the frequency and/or a respectiveimpedance value associated with a first transmitting antenna element ofthe one or more transmitting antenna elements to cause the firsttransmitting antenna element to operate in a first frequency band, andadaptively adjust the frequency and/or the respective impedance valueassociated with a second transmitting antenna element of the one or moretransmitting antenna elements to cause the second transmitting antennaelement to operate in a second frequency band, wherein the firstfrequency band is distinct from the second frequency band.

(C12) In some embodiments of any of C1-C11, the electronic device isplaced in contact with or close to a top surface of the RF charging pad.

(C13) In some embodiments of any of C1-C12, the respective component isa mechanical relay coupled with the respective adaptive load terminalfor switching the respective adaptive load terminal between open andshort states, and the impedance value is adaptively adjusted at therespective adaptive load terminal of the respective transmitting antennaelement by opening or closing the mechanical relay to switch between anopen or short circuit, respectively.

(C14) In some embodiments of any of C1-C13, the respective component isan application-specific integrated circuit (ASIC), and the respectiveimpedance value is adaptively adjusted by the ASIC to within a range ofvalues.

(C15) In some embodiments of any of C1-C14, the one or more processorsare configured to: adaptively adjust the frequency and/or the respectiveimpedance value by adaptively adjusting the frequency and a respectiveimpedance value at one or more of the plurality of adaptive loadterminals to determine a relative maximum amount of energy that istransferred to the RF receiver of the electronic device, and once themaximum amount of energy is determined, cause each of the one or moretransmitting antenna elements to respectively transmit the RF signals ata respective frequency and using a respective impedance value thatresulted in the maximum amount of energy transferred to the RF receiver.

(C16) In some embodiments of any of C1-C15, the one or more processorsmonitor the amount of energy that is transferred to the RF receiverbased at least in part on information received from the electronicdevice, the information identifying energy received at the RF receiverfrom the RF signals.

(C17) In some embodiments of any of C1-C16, the information receivedfrom the electronic device identifying received energy is sent using awireless communication protocol.

(C18) In some embodiments of any of C1-C17, the wireless communicationprotocol is bluetooth low energy (BLE).

(C19) In some embodiments of any of C1-C18, the one or more processorsmonitor the amount of energy transferred based at least in part on anamount of energy that is detected at the respective adaptive loadterminal.

Thus, wireless charging systems configured in accordance with theprinciples described herein are able to charge an electronic device thatis placed at any position on the RF charging pad and avoid wastingenergy by ensuring that energy transfer is constantly optimized.

In addition, wireless charging systems configured in accordance with theprinciples described herein are able to charge different electronicdevices that are tuned at different frequencies or frequency bands onthe same charging transmitter. In some embodiments, a transmitter with asingle antenna element can operate at multiple frequencies or frequencybands at the same time or at different times. In some embodiments, atransmitter with multiple antenna elements can operate at multiplefrequencies or frequency bands at the same time. That enables moreflexibility in the types and sizes of antennas that are included inreceiving devices.

In another aspect, dynamically-adjustable transmitting antennas areprovided. In the design of charging pads that allow receiving devices tobe placed at any position on the pad, radio-frequency-based solutionsoffer much promise. Because receiving antennas used inradio-frequency-based solutions may have different polarizations,transmitting antennas must also be designed that are able to transmit atdifferent polarizations, to ensure an efficient transfer of power fromthe transmitting to the receiving antennas. As such, there is a need fortransmitting antennas that may be dynamically adjusted to transmitenergy using different polarizations and embodiments discussed hereinaddress this need (see, e.g., descriptions and figures associated withnear-field antenna 2500).

(D1) In accordance with some embodiments, a near-field antenna isprovided. The near-field antenna (e.g., near-field antenna 2500, FIG.25A) includes: a reflector and four distinct coplanar antenna elements,offset from the reflector, where each of the four distinct antennaelements follows respective meandering patterns. Further, two antennaelements of the four coplanar antenna elements form a first dipoleantenna along a first axis, and another two antenna elements of the fourcoplanar antenna elements form a second dipole antenna along a secondaxis perpendicular to the first axis. The near-field antenna furtherincludes: (i) a power amplifier configured to feed electromagneticsignals to at least one of the first and second dipole antennas, (ii) animpedance-adjusting component configured to adjust an impedance of atleast one of the first and second dipole antennas, and (iii) switchcircuitry coupled to the power amplifier, the impedance-adjustingcomponent, and the first and second dipole antennas. The switchcircuitry is configured to: (A) switchably couple the first dipoleantenna to the power amplifier and the second dipole antenna to theimpedance-adjusting component, or (B) switchably couple the seconddipole antenna to the power amplifier and the first dipole antenna tothe impedance-adjusting component.

(D2) In accordance with some embodiments, a method is also provided thatis used to charge an electronic device through radio frequency (RF)power transmission using a near-field antenna. The method includesproviding the near-field antenna of D1. For example, the near-fieldantenna includes (i) a reflector, (ii) four distinct coplanar antennaelements, offset from the reflector, each of the four distinct antennaelements following respective meandering patterns, where: (A) twoantenna elements of the four coplanar antenna elements form a firstdipole antenna aligned with a first axis, and (B) another two antennaelements of the four coplanar antenna elements form a second dipoleantenna aligned with a second axis perpendicular to the first axis,(iii) switch circuitry coupled to at least two of the four coplanarantenna elements, (iv) a power amplifier coupled to the switchcircuitry, and (v) an impedance-adjusting component coupled to theswitch circuitry. The method further includes instructing the switchcircuitry to couple: (i) the first dipole antenna to the poweramplifier, and (ii) the second dipole antenna to the impedance-adjustingcomponent. The method further includes instructing the power amplifierto feed electromagnetic signals to the first dipole antenna via theswitch circuitry. In doing so, the electromagnetic signals, when fed tothe first dipole antenna, cause the first dipole antenna to radiateelectromagnetic signals to be received by a wireless-power-receivingdevice located within a threshold distance from the near-field antenna.In addition, an impedance of the second dipole antenna is adjusted bythe impedance-adjusting component so that the impedance of the seconddipole antenna differs from an impedance of the first dipole antenna.

(D3) In accordance with some embodiments, a non-transitorycomputer-readable storage medium is provided. The non-transitorycomputer-readable storage medium includes executable instructions that,when executed by one or more processors that are coupled with thenear-field antenna of D1, cause the near-field antenna of D1 to: (A)instruct the switch circuitry to couple: (i) the first dipole antenna tothe power amplifier, and (ii) the second dipole antenna to theimpedance-adjusting component, and (B) instruct the power amplifier tofeed electromagnetic signals to the first dipole antenna via the switchcircuitry. In doing so, the electromagnetic signals, when fed to thefirst dipole antenna, cause the first dipole antenna to radiateelectromagnetic signals to be received by a wireless-power-receivingdevice located within a threshold distance from the near-field antenna.In addition, an impedance of the second dipole antenna is adjusted bythe impedance-adjusting component so that the impedance of the seconddipole antenna differs from an impedance of the first dipole antenna.

(D4) In some embodiments of any of D1-D3, in a first mode of operationfor the near-field antenna, the switch circuitry couples (i) the firstdipole antenna to the power amplifier and (ii) the second dipole antennato the impedance-adjusting component. Further, in a second mode ofoperation for the near-field antenna, the switch circuitry couples (i)the second dipole antenna to the power amplifier and (ii) the firstdipole antenna to the impedance-adjusting component.

(D5) In some embodiments of D4, in the first mode of operation for thenear-field antenna, the first dipole antenna is to receiveelectromagnetic waves from the power amplifier and radiate the receivedelectromagnetic waves having a first polarization, and in the secondmode of operation for the near-field antenna, the second dipole antennais to receive electromagnetic waves from the power amplifier and radiatethe received electromagnetic waves having a second polarizationdifferent from the first polarization.

(D6) In some embodiments of any of D1-D5, a wireless-power-receivingdevice, located within a threshold distance from the near-field antenna,is configured to harvest the radiated electromagnetic waves and use theharvested electromagnetic waves to power or charge an electronic devicecoupled with the wireless-power-receiving device.

(D7) In some embodiments of any of D1-D6, the near-field antenna furtherincludes a controller configured to control operation of the switchcircuitry and the power amplifier.

(D8) In some embodiments of any of D1-D7, the controller is configuredto control operation of the switch circuitry and the power amplifierbased on one or more of: (i) a location of a wireless-power-receivingdevice, (ii) a polarization of a power-receiving-antenna of thewireless-power-receiving device, and (iii) a spatial orientation of thewireless-power-receiving device.

(D9) In some embodiments of any of D1-D8, the near-field antenna furtherincludes a first feed and a second feed. The first feed is connected toa first of the two antenna elements of the first dipole antenna and theswitch circuitry, and the first feed is configured to supplyelectromagnetic signals to the first antenna element of the first dipoleantenna that originate from the power amplifier when the power amplifieris switchably coupled to the first dipole antenna by the switchcircuitry (e.g., the near-field antenna is in the first mode ofoperation). The second feed is connected to a first of the other twoantenna elements of the second dipole antenna and the switch circuitry,and the second feed is configured to supply electromagnetic signals tothe first antenna element of the second dipole antenna that originatefrom the power amplifier when the power amplifier is switchably coupledto the second dipole antenna by the switch circuitry (e.g., thenear-field antenna is in the second mode of operation).

(D10) In some embodiments of any of D1-D9, a first antenna element ofthe four distinct coplanar antenna elements is a first pole of the firstdipole antenna and a second antenna element of the four distinctcoplanar antenna elements is a second pole of the first dipole antenna.In addition, a third antenna element of the four distinct coplanarantenna elements is a first pole of the second dipole antenna and afourth antenna element of the four distinct coplanar antenna elements isa second pole of the second dipole antenna.

(D11) In some embodiments of any of D1-D10, the two antenna elementsthat form the first dipole antenna each include two segments that areperpendicular to the first axis and the other two antenna elements thatform the second dipole antenna each include two segments that areparallel to the first axis. Put another way, the two antenna elementsthat form the first dipole antenna each include two segments that areparallel to the second axis and the other two antenna elements that formthe second dipole antenna each include two segments that areperpendicular to the second axis.

(D11.1) In some embodiments of any of D1-D11, each of the four distinctantenna elements includes: (i) a respective first plurality of segments,and (ii) a respective second plurality of segments interspersed betweeneach of the first plurality of segments.

(D12) In some embodiments of any of D1-D11.1, first lengths of segmentsin the first plurality of segments increase from a first end portion ofthe antenna element to a second end portion of the antenna element andseconds lengths of segments in the second plurality of segments increasefrom the first end portion of the antenna element to the second endportion of the antenna element.

(D13) In some embodiments of D12, the first lengths of the segments inthe first plurality of segments are different from the second lengths ofthe segments in the second plurality of segments.

(D14) In some embodiments of any of D12 and D13, the first lengths ofthe segments in the first plurality of segments are different from thesecond lengths of the segments in the second plurality of segments.

(D15) In some embodiments of D14, the first lengths of the segments inthe first plurality of segments toward the second end portion of theantenna element are greater than the second lengths of the segments inthe second plurality of segments toward the second end portion of theantenna element.

(D16) In some embodiments of any of D1-D15, the reflector is a solidmetal sheet of copper or a copper alloy.

(D17) In some embodiments of any of D1-D16, the reflector is configuredto reflect at least a portion of the electromagnetic signals radiated bythe first or second dipole antennas.

(D18) In some embodiments of any of D1-D17, the four distinct coplanarantenna elements are formed on or within a substrate.

(D19) In some embodiments of D18, the substrate comprises a metamaterialof a predetermined magnetic permeability or electrical permittivity.

(D20) In some embodiments of any of D1-D19, the respective meanderingpatterns are all the same.

(D21) In some embodiments of D20, the two antenna elements that form thefirst dipole antenna are aligned along the first axis such that therespective meandering patterns followed by each of the two antennaelements are mirror images of one another.

(D22) In some embodiments of any of D20-D21, the other two antennaelements that form the second dipole antenna are aligned along thesecond axis such that the respective meandering patterns followed byeach of the other two antenna elements are mirror images of one another.

(D23) In some embodiments of any of D1-D22, a first end portion of therespective meandering pattern followed by each of the four distinctantenna elements borders a same central portion of the near-fieldantenna, and a second end portion of the respective meandering patternfollowed by each of the four distinct antenna elements borders adistinct edge of the near-field antenna. Furthermore, a longestdimension of the respective meandering pattern followed by each of thefour distinct antenna elements is closer to the distinct edge of thenear-field antenna than to the same central portion of the near-fieldantenna.

(D24) In some embodiments of D23, a shortest dimension of the respectivemeandering pattern followed by each of the four distinct antennaelements is closer to the same central portion of the near-field antennathan the distinct edge of the near-field antenna.

(E1) In accordance with some embodiments, a near-field antenna isprovided. The near-field antenna (e.g., near-field antenna 2500, FIG.25A) includes four distinct coplanar antenna elements, where eachantenna element occupies a distinct quadrant of the near-field antenna(e.g., one of the quadrants 2570-A to 2570-D). Further, a width of eachof the four distinct antenna elements increases, in a meanderingfashion, from a central portion of the near-field antenna to arespective edge of the near-field antenna. In other words, a longestdimension of each of the four distinct antenna elements is near (i.e.,adjacent/borders) the respective edge of the near-field antenna, andconversely, a shortest dimension of each of the four distinct antennaelements is near (i.e., adjacent/borders) the central portion of thenear-field antenna.

(E2) In some embodiments of E1, two antenna elements of the fourcoplanar antenna elements form a first dipole antenna along a firstaxis, and another two antenna elements of the four coplanar antennaelements form a second dipole antenna along a second axis perpendicularto the first axis.

(E3) In some embodiments of E2, the two antenna elements that form thefirst dipole antenna are aligned along the first axis such that therespective meandering patterns followed by each of the two antennaelements are mirror images of one another.

(E4) In some embodiments of E3, the other two antenna elements that formthe second dipole antenna are aligned along the second axis such thatthe respective meandering patterns followed by each of the other twoantenna elements are mirror images of one another.

Note that the various embodiments described above can be combined withany other embodiments described herein. The features and advantagesdescribed in the specification are not all inclusive and, in particular,many additional features and advantages will be apparent to one ofordinary skill in the art in view of the drawings, specification, andclaims. Moreover, it should be noted that the language used in thespecification has been principally selected for readability andinstructional purposes, and not intended to circumscribe or limit theinventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

So that the present disclosure can be understood in greater detail, amore particular description may be had by reference to the features ofvarious embodiments, some of which are illustrated in the appendeddrawings. The appended drawings, however, merely illustrate pertinentfeatures of the present disclosure and are therefore not to beconsidered limiting, for the description may admit to other effectivefeatures.

FIG. 1A is a block diagram of an RF wireless power transmission system,in accordance with some embodiments.

FIG. 1B is a block diagram showing components of an example RF chargingpad that includes an RF power transmitter integrated circuit and antennazones, in accordance with some embodiments.

FIG. 1C is a block diagram showing components of an example RF chargingpad that includes an RF power transmitter integrated circuit coupled toa switch, in accordance with some embodiments.

FIG. 2A is a block diagram illustrating an example RF charging pad, inaccordance with some embodiments.

FIG. 2B is a block diagram illustrating an example receiver device, inaccordance with some embodiments.

FIG. 3A is a high-level block diagram of an RF charging pad, inaccordance with some embodiments.

FIGS. 3B-3C are high-level block diagrams showing a portion of an RFcharging pad, in accordance with some embodiments.

FIG. 3D is a block diagram of a simplified circuit that illustratesenergy flow within sections of an antenna element that is transmittingan RF signal, in accordance with some embodiments.

FIG. 4 is a schematic of a transmitting antenna element with twoterminals, in accordance with some embodiments.

FIG. 5 is a flow chart of a method of charging an electronic devicethrough radio frequency (RF) power transmission.

FIGS. 6A-6E are schematics showing various configurations for individualantenna elements within an RF charging pad, in accordance with someembodiments.

FIGS. 7A-7D are schematics of an antenna element for an RF receiver, inaccordance with some embodiments.

FIG. 8 is a schematic of an RF charging pad with a plurality oftransmitting antenna elements (or unit cells), in accordance with someembodiments.

FIGS. 9A-9B are flow diagrams showing a method 900 of selectivelyactivating one or more antenna zones in a near-field charging pad, inaccordance with some embodiments.

FIG. 10 is an overview showing a process of selectively activating oneor more antenna zones in a near-field charging pad, in accordance withsome embodiments.

FIGS. 11A-11E are flow diagrams showing various aspects of selectivelyactivating one or more antenna zones in a near-field charging pad, inaccordance with some embodiments.

FIG. 12 is a schematic of a transmitting antenna element with aplurality of adaptive loads of an RF charging pad, in accordance withsome embodiments.

FIG. 13 is a flow chart of a method of charging an electronic devicethrough radio frequency (RF) power transmission by using at least one RFantenna with a plurality of adaptive loads, in accordance with someembodiments.

FIGS. 14A-14D are schematics showing various configurations forindividual antenna elements that can operate at multiple frequencies orfrequency bands within an RF charging pad, in accordance with someembodiments.

FIG. 15 is schematic showing an example configuration for an individualantenna element that can operate at multiple frequencies or frequencybands by adjusting the length of the antenna element, in accordance withsome embodiments.

FIGS. 16A and 16B are schematic illustrations of an exemplary system,according to an embodiment.

FIGS. 17A-17D are schematic illustrations of an exemplary system,according to an embodiment.

FIG. 18 is a schematic illustration of an exemplary system, according toan embodiment.

FIG. 19 is a schematic illustration of an exemplary system, according toan embodiment.

FIG. 20 is a schematic illustration of an exemplary system, according toan embodiment.

FIG. 21 is a schematic illustration of an exemplary system, according toan embodiment.

FIG. 22 is a schematic illustration of an exemplary system, according toan embodiment.

FIG. 23 is a schematic illustration of an exemplary system, according toan embodiment.

FIGS. 24A and 24B are schematic illustrations of an exemplary system,according to an embodiment.

FIG. 25A shows an isometric view of a near-field antenna in accordancewith some embodiments.

FIG. 25B shows another isometric view of a near-field antenna inaccordance with some embodiments.

FIGS. 25C-25D show different side views of a near-field antenna inaccordance with some embodiments.

FIG. 25E shows another side view of a near-field antenna in accordancewith some embodiments.

FIG. 25F shows a representative radiating element following a meanderingpattern in accordance with some embodiments.

FIG. 25G shows a top view of a near-field antenna in accordance withsome embodiments.

FIG. 25H shows another top view of a near-field antenna in accordancewith some embodiments.

FIG. 26 is a block diagram of a control system used for controllingoperation of a near-field antenna in accordance with some embodiments/.

FIG. 27 shows a radiation pattern generated by the near-field antennawith a reflector of FIG. 25A.

FIGS. 28A to 28C show additional radiation patterns generated by thenear-field antenna of FIG. 25A.

FIGS. 29A and 29B show concentrations of energy radiated and absorbed bydipole antennas of a near-field antenna in accordance with someembodiments.

FIG. 30 is a flow diagram showing a method of wireless powertransmission in accordance with some embodiments.

In accordance with common practice, the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may not depict all of the componentsof a given system, method or device. Finally, like reference numeralsmay be used to denote like features throughout the specification andfigures.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings. In the following detaileddescription, numerous specific details are set forth in order to providea thorough understanding of the various described embodiments. However,it will be apparent to one of ordinary skill in the art that the variousdescribed embodiments may be practiced without these specific details.In other instances, well-known methods, procedures, components,circuits, and networks have not been described in detail so as not tounnecessarily obscure aspects of the embodiments.

FIG. 1A is a block diagram of an RF wireless power transmission systemin accordance with some embodiments. In some embodiments, the RFwireless power transmission system 150 includes a RF charging pad 100(also referred to herein as a near-field (NF) charging pad 100 or RFcharging pad 100). In some embodiments, the RF charging pad 100 includesan RF power transmitter integrated circuit 160 (described in more detailbelow). In some embodiments, the RF charging pad 100 includes one ormore communications components 204 (e.g., wireless communicationcomponents, such as WI-FI or BLUETOOTH radios), discussed in more detailbelow with reference to FIG. 2A. In some embodiments, the RF chargingpad 100 also connects to one or more power amplifier units 108-1, . . .108-n to control operation of the one or more power amplifier units whenthey drive an external TX antenna array 210. In some embodiments, RFpower is controlled and modulated at the RF charging pad 100 via switchcircuitry as to enable the RF wireless power transmission system to sendRF power to one or more wireless receiving devices via the TX antennaarray 210. Example power amplifier units are discussed in further detailbelow with reference to FIG. 3A.

In some embodiments, the communication component(s) 204 enablecommunication between the RF charging pad 100 and one or morecommunication networks. In some embodiments, the communicationcomponent(s) 204 are capable of data communications using any of avariety of custom or standard wireless protocols (e.g., IEEE 802.15.4,Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a,WirelessHART, MiWi, etc.) custom or standard wired protocols (e.g.,Ethernet, HomePlug, etc.), and/or any other suitable communicationprotocol, including communication protocols not yet developed as of thefiling date of this document.

FIG. 1B is a block diagram of the RF power transmitter integratedcircuit 160 (the “integrated circuit”) in accordance with someembodiments. In some embodiments, the integrated circuit 160 includes aCPU subsystem 170, an external device control interface, an RFsubsection for DC to RF power conversion, and analog and digital controlinterfaces interconnected via an interconnection component, such as abus or interconnection fabric block 171. In some embodiments, the CPUsubsystem 170 includes a microprocessor unit (CPU) 202 with relatedRead-Only-Memory (ROM) 172 for device program booting via a digitalcontrol interface, e.g. an I²C port, to an external FLASH containing theCPU executable code to be loaded into the CPU Subsystem Random AccessMemory (RAM) 174 (e.g., memory 206, FIG. 2A) or executed directly fromFLASH. In some embodiments, the CPU subsystem 170 also includes anencryption module or block 176 to authenticate and secure communicationexchanges with external devices, such as wireless power receivers thatattempt to receive wirelessly delivered power from the RF charging pad100.

In some embodiments, executable instructions running on the CPU (such asthose shown in the memory 206 in FIG. 2A and described below) are usedto manage operation of the RF charging pad 100 and to control externaldevices through a control interface, e.g., SPI control interface 175,and the other analog and digital interfaces included in the RF powertransmitter integrated circuit 160. In some embodiments, the CPUsubsystem also manages operation of the RF subsection of the RF powertransmitter integrated circuit 160, which includes an RF localoscillator (LO) 177 and an RF transmitter (TX) 178. In some embodiments,the RF LO 177 is adjusted based on instructions from the CPU subsystem170 and is thereby set to different desired frequencies of operation,while the RF TX converts, amplifies, modulates the RF output as desiredto generate a viable RF power level.

In some embodiments, the RF power transmitter integrated circuit 160provides the viable RF power level (e.g., via the RF TX 178) to anoptional beamforming integrated circuit (IC) 109, which then providesphase-shifted signals to one or more power amplifiers 108. In someembodiments, the beamforming IC 109 is used to ensure that powertransmission signals sent using two or more antennas 210 (e.g., eachantenna 210 may be associated with a different antenna zones 290 or mayeach belong to a single antenna zone 290) to a particular wireless powerreceiver are transmitted with appropriate characteristics (e.g., phases)to ensure that power transmitted to the particular wireless powerreceiver is maximized (e.g., the power transmission signals arrive inphase at the particular wireless power receiver). In some embodiments,the beamforming IC 109 forms part of the RF power transmitter IC 160.

In some embodiments, the RF power transmitter integrated circuit 160provides the viable RF power level (e.g., via the RF TX 178) directly tothe one or more power amplifiers 108 and does not use the beamforming IC109 (or bypasses the beamforming IC if phase-shifting is not required,such as when only a single antenna 210 is used to transmit powertransmission signals to a wireless power receiver).

In some embodiments, the one or more power amplifiers 108 then provideRF signals to the antenna zones 290 for transmission to wireless powerreceivers that are authorized to receive wirelessly delivered power fromthe RF charging pad 100. In some embodiments, each antenna zone 290 iscoupled with a respective PA 108 (e.g., antenna zone 290-1 is coupledwith PA 108-1 and antenna zone 290-N is coupled with PA 108-N). In someembodiments, multiple antenna zones are each coupled with a same set ofPAs 108 (e.g., all PAs 108 are coupled with each antenna zone 290).Various arrangements and couplings of PAs 108 to antenna zones 290 allowthe RF charging pad 100 to sequentially or selectively activatedifferent antenna zones in order to determine the most efficient antennazone 290 to use for transmitting wireless power to a wireless powerreceiver (as explained in more detail below in reference to FIGS. 9A-9B,10, and 11A-11E). In some embodiments, the one or more power amplifiers108 are also in communication with the CPU subsystem 170 to allow theCPU 202 to measure output power provided by the PAs 108 to the antennazones of the RF charging pad 100.

FIG. 1B also shows that, in some embodiments, the antenna zones 290 ofthe RF charging pad 100 may include one or more antennas 210A-N. In someembodiments, each antenna zones of the plurality of antenna zonesincludes one or more antennas 210 (e.g., antenna zone 290-1 includes oneantenna 210-A and antenna zones 290-N includes multiple antennas 210).In some embodiments, a number of antennas included in each of theantenna zones is dynamically defined based on various parameters, suchas a location of a wireless power receiver on the RF charging pad 100.In some embodiments, the antenna zones may include one or more of themeandering line antennas described in more detail below. In someembodiments, each antenna zone 290 may include antennas of differenttypes (e.g., a meandering line antenna and a loop antenna), while inother embodiments each antenna zone 290 may include a single antenna ofa same type (e.g., all antenna zones 290 include one meandering lineantenna), while in still other embodiments, the antennas zones mayinclude some antenna zones that include a single antenna of a same typeand some antenna zones that include antennas of different types. Antennazones are also described in further detail below.

In some embodiments, the RF charging pad 100 may also include atemperature monitoring circuit that is in communication with the CPUsubsystem 170 to ensure that the RF charging pad 100 remains within anacceptable temperature range. For example, if a determination is madethat the RF charging pad 100 has reached a threshold temperature, thenoperation of the RF charging pad 100 may be temporarily suspended untilthe RF charging pad 100 falls below the threshold temperature.

By including the components shown for RF power transmitter circuit 160(FIG. 1B) on a single chip, such integrated circuits are able to manageoperations at the integrated circuits more efficiently and quickly (andwith lower latency), thereby helping to improve user satisfaction withthe charging pads that are managed by these integrated circuits. Forexample, the RF power transmitter circuit 160 is cheaper to construct,has a smaller physical footprint, and is simpler to install.Furthermore, and as explained in more detail below in reference to FIG.2A, the RF power transmitter circuit 160 may also include a secureelement module 234 (e.g., included in the encryption block 176 shown inFIG. 1B) that is used in conjunction with a secure element module 282(FIG. 2B) or a receiver 104 to ensure that only authorized receivers areable to receive wirelessly delivered power from the RF charging pad 100(FIG. 1B).

FIG. 1C is a block diagram of a charging pad 294 in accordance with someembodiments. The charging pad 294 is an example of the charging pad 100(FIG. 1A), however, one or more components included in the charging pad100 are not included in the charging pad 294 for ease of discussion andillustration.

The charging pad 294 includes an RF power transmitter integrated circuit160, one or more power amplifiers 108, and a transmitter antenna array290 having multiple antenna zones. Each of these components is describedin detail above with reference to FIGS. 1A and 1B. Additionally, thecharging pad 294 includes a switch 295, positioned between the poweramplifiers 108 and the antenna array 290, having a plurality of switches297-A, 297-B, . . . 297-N. The switch 295 is configured to switchablyconnect one or more power amplifiers 108 with one or more antenna zonesof the antenna array 290 in response to control signals provided by theRF power transmitter integrated circuit 160.

To accomplish the above, each switch 297 is coupled with (e.g., providesa signal pathway to) a different antenna zone of the antenna array 290.For example, switch 297-A may be coupled with a first antenna zone 290-1(FIG. 1B) of the antenna array 290, switch 297-B may be coupled with asecond antenna zone 290-2 of the antenna array 290, and so on. Each ofthe plurality of switches 297-A, 297-B, . . . 297-N, once closed,creates a unique pathway between a respective power amplifier 108 (ormultiple power amplifiers 108) and a respective antenna zone of theantenna array 290. Each unique pathway through the switch 295 is used toselectively provide RF signals to specific antenna zones of the antennaarray 290. It is noted that two or more of the plurality of switches297-A, 297-B, . . . 297-N may be closed at the same time, therebycreating multiple unique pathways to the antenna array 290 that may beused simultaneously.

In some embodiments, the RF power transmitter integrated circuit 160 iscoupled to the switch 295 and is configured to control operation of theplurality of switches 297-A, 297-B, . . . 297-N (illustrated as a“control out” signal in FIGS. 1A and 1C). For example, the RF powertransmitter integrated circuit 160 may close a first switch 297-A whilekeeping the other switches open. In another example, the RF powertransmitter integrated circuit 160 may close a first switch 297-A and asecond switch 297-B, and keep the other switches open (various othercombinations and configuration are possible). Moreover, the RF powertransmitter integrated circuit 160 is coupled to the one or more poweramplifiers 108 and is configured to generate a suitable RF signal (e.g.,the “RF Out” signal) and provide the RF signal to the one or more poweramplifiers 108. The one or more power amplifiers 108, in turn, areconfigured to provide the RF signal to one or more antenna zones of theantenna array 290 via the switch 295, depending on which switches 297 inthe switch 295 are closed by the RF power transmitter integrated circuit160.

To further illustrate, as described in some embodiments below, thecharging pad is configured to transmit test power transmission signalsand/or regular power transmission signals using different antenna zones,e.g., depending on a location of a receiver on the charging pad.Accordingly, when a particular antenna zone is selected for transmittingtest signals or regular power signals, a control signal is sent to theswitch 295 from the RF power transmitter integrated circuit 160 to causeat least one switch 297 to close. In doing so, an RF signal from atleast one power amplifier 108 can be provided to the particular antennazone using a unique pathway created by the now-closed at least oneswitch 297.

In some embodiments, the switch 295 may be part of (e.g., internal to)the antenna array 290. Alternatively, in some embodiments, the switch295 is separate from the antenna array 290 (e.g., the switch 295 may bea distinct component, or may be part of another component, such as thepower amplifier(s) 108). It is noted that any switch design capable ofaccomplishing the above may be used, and the design of the switch 295illustrated in FIG. 1C is merely one example.

FIG. 2A is a block diagram illustrating certain components of an RFcharging pad 100 in accordance with some embodiments. In someembodiments, the RF charging pad 100 includes an RF power transmitter IC160 (and the components included therein, such as those described abovein reference to FIGS. 1A-1B), memory 206 (which may be included as partof the RF power transmitter IC 160, such as nonvolatile memory 206 thatis part of the CPU subsystem 170), and one or more communication buses208 for interconnecting these components (sometimes called a chipset).In some embodiments, the RF charging pad 100 includes one or moresensor(s) 212 (discussed below). In some embodiments, the RF chargingpad 100 includes one or more output devices such as one or moreindicator lights, a sound card, a speaker, a small display fordisplaying textual information and error codes, etc. In someembodiments, the RF charging pad 100 includes a location detectiondevice, such as a GPS (global positioning satellite) or othergeo-location receiver, for determining the location of the RF chargingpad 100.

In some embodiments, the one or more sensor(s) 212 include one or morethermal radiation sensors, ambient temperature sensors, humiditysensors, IR sensors, occupancy sensors (e.g., RFID sensors), ambientlight sensors, motion detectors, accelerometers, and/or gyroscopes.

The memory 206 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 206, or alternatively the non-volatilememory within memory 206, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 206, or thenon-transitory computer-readable storage medium of the memory 206,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   -   Operating logic 216 including procedures for handling various        basic system services and for performing hardware dependent        tasks;    -   Communication module 218 for coupling to and/or communicating        with remote devices (e.g., remote sensors, transmitters,        receivers, servers, mapping memories, etc.) in conjunction with        wireless communication component(s) 204;    -   Sensor module 220 for obtaining and processing sensor data        (e.g., in conjunction with sensor(s) 212) to, for example,        determine the presence, velocity, and/or positioning of object        in the vicinity of the RF charging pad 100;    -   Power-wave generating module 222 for generating and transmitting        power transmission signals (e.g., in conjunction with antenna        zones 290 and the antennas 210 respectively included therein),        including but not limited to, forming pocket(s) of energy at        given locations. Power-wave generating module 222 may also be        used to modify transmission characteristics used to transmit        power transmission signals by individual antenna zones; and    -   Database 224, including but not limited to:        -   Sensor information 226 for storing and managing data            received, detected, and/or transmitted by one or more            sensors (e.g., sensors 212 and/or one or more remote            sensors);        -   Device settings 228 for storing operational settings for the            RF charging pad 100 and/or one or more remote devices;        -   Communication protocol information 230 for storing and            managing protocol information for one or more protocols            (e.g., custom or standard wireless protocols, such as            ZigBee, Z-Wave, etc., and/or custom or standard wired            protocols, such as Ethernet); and        -   Mapping data 232 for storing and managing mapping data            (e.g., mapping one or more transmission fields);    -   a secure element module 234 for determining whether a wireless        power receiver is authorized to receive wirelessly delivered        power from the RF charging pad 100; and    -   an antenna zone selecting and tuning module 237 for coordinating        a process of transmitting test power transmission signals with        various antenna zones to determine which antenna zone or zones        should be used to wirelessly deliver power to various wireless        power receivers (as is explained in more detail below in        reference to FIGS. 9A-9B, 100, and 11A-11E).

Each of the above-identified elements (e.g., modules stored in memory206 of the RF charging pad 100) is optionally stored in one or more ofthe previously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 206, optionally, stores a subset of the modules and datastructures identified above.

FIG. 2B is a block diagram illustrating a representative receiver device104 (also sometimes called a receiver, power receiver, or wireless powerreceiver) in accordance with some embodiments. In some embodiments, thereceiver device 104 includes one or more processing units (e.g., CPUs,ASICs, FPGAs, microprocessors, and the like) 252, one or morecommunication components 254, memory 256, antenna(s) 260, powerharvesting circuitry 259, and one or more communication buses 258 forinterconnecting these components (sometimes called a chipset). In someembodiments, the receiver device 104 includes one or more sensor(s) 262such as the one or sensors 212 described above with reference to FIG.2A. In some embodiments, the receiver device 104 includes an energystorage device 261 for storing energy harvested via the power harvestingcircuitry 259. In various embodiments, the energy storage device 261includes one or more batteries, one or more capacitors, one or moreinductors, and the like.

In some embodiments, the power harvesting circuitry 259 includes one ormore rectifying circuits and/or one or more power converters. In someembodiments, the power harvesting circuitry 259 includes one or morecomponents (e.g., a power converter) configured to convert energy frompower waves and/or energy pockets to electrical energy (e.g.,electricity). In some embodiments, the power harvesting circuitry 259 isfurther configured to supply power to a coupled electronic device, suchas a laptop or phone. In some embodiments, supplying power to a coupledelectronic device include translating electrical energy from an AC formto a DC form (e.g., usable by the electronic device).

In some embodiments, the antenna(s) 260 include one or more of themeandering line antennas that are described in further detail below.

In some embodiments, the receiver device 104 includes one or more outputdevices such as one or more indicator lights, a sound card, a speaker, asmall display for displaying textual information and error codes, etc.In some embodiments, the receiver device 104 includes a locationdetection device, such as a GPS (global positioning satellite) or othergeo-location receiver, for determining the location of the receiverdevice 103.

In various embodiments, the one or more sensor(s) 262 include one ormore thermal radiation sensors, ambient temperature sensors, humiditysensors, IR sensors, occupancy sensors (e.g., RFID sensors), ambientlight sensors, motion detectors, accelerometers, and/or gyroscopes.

The communication component(s) 254 enable communication between thereceiver 104 and one or more communication networks. In someembodiments, the communication component(s) 254 are capable of datacommunications using any of a variety of custom or standard wirelessprotocols (e.g., IEEE 802.15.4, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave,Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) custom orstandard wired protocols (e.g., Ethernet, HomePlug, etc.), and/or anyother suitable communication protocol, including communication protocolsnot yet developed as of the filing date of this document.

The communication component(s) 254 include, for example, hardwarecapable of data communications using any of a variety of custom orstandard wireless protocols (e.g., IEEE 802.15.4, Wi-Fi, ZigBee,6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART,MiWi, etc.) and/or any of a variety of custom or standard wiredprotocols (e.g., Ethernet, HomePlug, etc.), or any other suitablecommunication protocol, including communication protocols not yetdeveloped as of the filing date of this document.

The memory 256 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 256, or alternatively the non-volatilememory within memory 256, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 256, or thenon-transitory computer-readable storage medium of the memory 256,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   -   Operating logic 266 including procedures for handling various        basic system services and for performing hardware dependent        tasks;    -   Communication module 268 for coupling to and/or communicating        with remote devices (e.g., remote sensors, transmitters,        receivers, servers, mapping memories, etc.) in conjunction with        communication component(s) 254;    -   Sensor module 270 for obtaining and processing sensor data        (e.g., in conjunction with sensor(s) 262) to, for example,        determine the presence, velocity, and/or positioning of the        receiver 103, a RF charging pad 100, or an object in the        vicinity of the receiver 103;    -   Wireless power-receiving module 272 for receiving (e.g., in        conjunction with antenna(s) 260 and/or power harvesting        circuitry 259) energy from power waves and/or energy pockets;        optionally converting (e.g., in conjunction with power        harvesting circuitry 259) the energy (e.g., to direct current);        transferring the energy to a coupled electronic device; and        optionally storing the energy (e.g., in conjunction with energy        storage device 261); and    -   Database 274, including but not limited to:        -   Sensor information 276 for storing and managing data            received, detected, and/or transmitted by one or more            sensors (e.g., sensors 262 and/or one or more remote            sensors);        -   Device settings 278 for storing operational settings for the            receiver 103, a coupled electronic device, and/or one or            more remote devices; and        -   Communication protocol information 280 for storing and            managing protocol information for one or more protocols            (e.g., custom or standard wireless protocols, such as            ZigBee, Z-Wave, etc., and/or custom or standard wired            protocols, such as Ethernet); and    -   a secure element module 282 for providing identification        information to the RF charging pad 100 (e.g., the RF charging        pad 100 uses the identification information to determine if the        wireless power receiver 104 is authorized to receive wirelessly        delivered power).

Each of the above-identified elements (e.g., modules stored in memory256 of the receiver 104) is optionally stored in one or more of thepreviously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 256, optionally, stores a subset of the modules and datastructures identified above. Furthermore, the memory 256, optionally,stores additional modules and data structures not described above, suchas an identifying module for identifying a device type of a connecteddevice (e.g., a device type for an electronic device that is coupledwith the receiver 104).

Turning now to FIGS. 3A through 8, embodiments of the RF charging pad100 are shown that include a component for modifying impedance values(e.g., a load pick) at various antennas of the RF charging pad 100, anddescriptions of antennas that include a conductive line forming ameandering line pattern are also provided in reference to these figures.

As shown in FIG. 3A, some embodiments include an RF charging pad 100that includes a load pick 106 to allow for modifying impedance values atvarious antennas of the RF charging pad 100. In some embodiments, the RFcharging pad 100 includes one or more antenna elements that are eachpowered/fed by a respective power amplifier switch circuit 103 at afirst end and a respective adaptive load terminal 102 at a second end(additional details and descriptions of the one or more antenna elementsare provided below in reference to FIGS. 3B-3C).

In some embodiments, the RF charging pad 100 also includes (or is incommunication with) a central processing unit 110 (also referred to hereas processor 110). In some embodiments, the processor 110 is a componentof a single integrated circuit that is responsible for managingoperations of the RF charging pad 100, such as the CPU 202 illustratedin FIG. 1B and included as a component of the RF power transmitterintegrated circuit 160. In some embodiments, the processor 110 isconfigured to control RF signal frequencies and to control impedancevalues at each of the adaptive load terminals 102 (e.g., bycommunicating with the load pick or adaptive load 106, which may be anapplication-specific integrated circuit (ASIC), or a variable resister,to generate various impedance values). In some embodiments, the loadpick 106 is an electromechanical switch that is placed in either an openor shorted state.

In some embodiments, an electronic device (e.g., a device that includesa receiver 104 as an internally or externally connected component, suchas a remote that is placed on top of a charging pad 100 that may beintegrated within a housing of a streaming media device or a projector)and uses energy transferred from one or more RF antenna elements of thecharging pad 100 to the receiver 104 to charge a battery and/or todirectly power the electronic device.

In some embodiments, the RF charging pad 100 is configured with morethan one input terminal for receiving power (from power amplifier (PA)108, FIG. 3A) and more than one output or adaptive load terminal 102. Insome embodiments, the adaptive load terminals 102 at a particular zoneof the RF charging pad 100 (e.g., a zone that includes antenna elementslocated underneath a position at which an electronic device (with aninternally or externally connected RF receiver 104) to be charged isplaced on the charging pad) are optimized in order to maximize powerreceived by the receiver 104. For example, the CPU 110 upon receiving anindication that an electronic device with an internally or externallyconnected RF receiver 104 has been placed on the pad 100 in a particularzone 105 (the zone 105 includes a set of antenna elements) may adapt theset of antenna elements to maximize power transferred to the RF receiver104. Adapting the set of antenna elements may include the CPU 110commanding load pick 106 to try various impedance values for adaptiveload terminals 102 that are associated with the set of antenna elements.For example, the impedance value for a particular conductive line at anantenna element is given by the complex value of Z=A+jB (where A is thereal part of the impedance value and B is the imaginary part, e.g.,0+j0, 1000+j0, 0+50j, or 25+j75, etc.), and the load pick adjusts theimpedance value to maximize the amount of energy transferred from theset of antenna elements to the RF receiver 104. In some embodiments,adapting the set of antenna elements also or alternatively includes theCPU 110 causing the set of antenna elements to transmit RF signals atvarious frequencies until a frequency is found at which a maximum amountof energy is transferred to the RF receiver 104. In some embodiments,adjusting the impedance value and/or the frequencies at which the set ofantenna elements transmits causes changes to the amount of energytransferred to the RF receiver 104. In this way, the amount of energytransferred to the RF receiver 104 is maximized (e.g., to transfer atleast 75% of the energy transmitted by antenna elements of the pad 100to the receiver 104, and in some embodiments, adjusting the impedancevalue and/frequencies may allow up to 98% of the energy transmitted tobe received by the receiver 104) may be received at any particular pointon the pad 100 at which the RF receiver 104 might be placed.

In some embodiments, the input circuit that includes the power amplifier108 can additionally include a device that can change frequencies of theinput signal, or a device that can operate at multiple frequencies atthe same time, such as an oscillator or a frequency modulator.

In some embodiments, the CPU 110 determines that a maximum amount ofenergy is being transferred to the RF receiver 104 when the amount ofenergy transferred to the RF receiver 104 crosses a predeterminedthreshold (e.g., 75% or more of transmitted energy is received, such asup to 98%) or by testing transmissions with a number of impedance and/orfrequency values and then selecting the combination of impedance andfrequency that results in maximum energy being transferred to the RFreceiver 104 (as described in reference to the adaptation scheme below).

In some embodiments, an adaptation scheme is employed to adaptivelyadjust the impedance values and/or frequencies of the RF signal(s)emitted from the RF antenna(s) 120 of the charging pad 100, in order todetermine which combinations of frequency and impedance result inmaximum energy transfer to the RF receiver 104. For example, theprocessor 110 that is connected to the charging pad 100 tries differentfrequencies (i.e., in the allowed operating frequency range or ranges)at a given location of the RF charging pad 100 (e.g., a zone or area ofthe RF charging pad 100 that includes one or more RF antenna elementsfor transmitting RF signals, such as zone 105 of FIG. 3A) to attempt toadaptively optimize for better performance. For example, a simpleoptimization either opens/disconnects or closes/shorts each loadterminal to ground (in embodiments in which a relay is used to switchbetween these states), and may also cause RF antennas within the zone totransmit at various frequencies. In some embodiments, for eachcombination of relay state (open or shorted) and frequency, the energytransferred to the receiver 104 is monitored and compared to energytransferred when using other combinations. The combination that resultsin maximum energy transfer to the receiver 104 is selected and used tocontinue to transmitting the one or more RF signals to the receiver 104.In some embodiments, the adaptation scheme described above is performedas a part of the methods described below in reference to FIGS. 9A-9B,10, and 11A-11E to help maximize an amount of energy transferred by theRF charging pad 100 to the receiver 104.

As another example, if five frequencies in the ISM band are utilized bythe pad 100 for transmitting radio frequency waves and the load pick 106is an electromechanical relay for switching between open and shortedstates, then employing the adaptation scheme would involve trying 10combinations of frequencies and impedance values for each antennaelement 120 or for a zone of antenna elements 120 and selecting thecombination that results in best performance (i.e., results in mostpower received at receiver 104, or most power transferred from the pad100 to the RF receiver 104).

The industrial, scientific, and medical radio bands (ISM bands) refersto a group of radio bands or parts of the radio spectrum that areinternationally reserved for the use of radio frequency (RF) energyintended for scientific, medical and industrial requirements rather thanfor communications. In some embodiments, all ISM bands (e.g., 40 MHz,900 MHz, 2.4 GHz, 5.8 GHz, 24 GHz, 60 GHz, 122 GHz, and 245 GHz) may beemployed as part of the adaptation scheme. As one specific example, ifthe charging pad 100 is operating in the 5.8 GHz band, then employingthe adaptation scheme would include transmitting RF signals and thenadjusting the frequency at predetermined increments (e.g., 50 MHzincrements, so frequencies of 5.75 GHz, 5.755 GHz, 5.76 GHz, and so on).In some embodiments, the predetermined increments may be 5, 10 15, 20,50 MHz increments, or any other suitable increment.

In some embodiments, the antenna elements 120 of the pad 100 may beconfigured to operate in two distinct frequency bands, e.g., a firstfrequency band with a center frequency of 915 MHz and a second frequencyband with a center frequency of 5.8 GHz. In these embodiments, employingthe adaptation scheme may include transmitting RF signals and thenadjusting the frequency at first predetermined increments until a firstthreshold value is reached for the first frequency band and thenadjusting the frequency at second predetermined increments (which may ormay not be the same as the first predetermined increments) until asecond threshold value is reached for the second frequency band. Forexample, the antenna elements 120 may be configured to transmit at 902MHz, 915 MHz, 928 MHZ (in the first frequency band) and then at 5.795GHz, 5.8 GHz, and 5.805 GHz (in the second frequency band). Additionaldetails regarding antenna elements that are capable of operating atmultiple frequencies are provided below in reference to FIGS. 14A-14Dand 15.

Turning now to FIGS. 3B-3C, high-level block diagrams showing a portionof an RF charging pad are illustrated, in accordance with someembodiments.

FIG. 3B shows a schematic of a single TX antenna 120 (which may be apart of an antenna zone that includes one or an array of such antennas120, all forming the charging pad 100 that is shown in FIG. 3A). In someembodiments, the TX antenna 120 is also referred to as a TX antennaelement 120. In some circumstances, an RF receiving unit/antenna (RX)(or a device that includes the receiving unit 104 as an internally orexternally connected component) is placed on top of a portion of the pad100 that includes the TX antenna 120 (which includes a conductive linethat forms a meandered line arrangement, as shown in FIG. 3B).

In some embodiments, the receiver 104 has no direct contact to ametallic conductive line of the single TX antenna 120 and is justcoupled (i.e. in near-field zone) to the TX antenna 120.

In some embodiments, the TX antenna 120 has two or more terminals (orports) that are labeled as 121 (which may be a respective one of theterminals 102 of FIG. 3A) and 123 (which may be connected to arespective one of the PA switch circuits 103 of FIG. 3A) in FIG. 3B. Insome embodiments, the source of power (from the power amplifier or PA)is connected to terminal 123 and an adaptive load (e.g., anelectromechanical switch or ASIC) is connected to terminal 121. In someembodiments, the adaptive load is formed generally as a compleximpedance which may have both real and imaginary parts (i.e., a complexadaptive load can be formed using active devices (e.g., integratedcircuits or chips made of transistors) or passive devices formed byinductors/capacitors and resistors). In some embodiments, the compleximpedance is given by the formula Z=A+jB (e.g., 0+j0, 100+j0, 0+50j, andetc.), as discussed above.

In some embodiments, the receiver 104 may also be considered as a thirdterminal. To eliminate wasted energy, the receiver 104 should beconfigured to absorb a maximum amount (e.g., 75% or more, such as 98%)of the induced power that travels from terminal 123 and towards terminal121. In some embodiments, processor 110 is connected to the receiver 104through a feedback loop (e.g., by exchanging messages using ashort-range communication protocol, such by BLUETOOTH low energy (BLE)to exchange messages). In some alternative embodiments, the feedbackloop from the receiver back to the CPU at the transmitter may utilize asame frequency band as the power transmission signals transmitted by thepad 100, rather than using a separate communication protocol and/or adifferent frequency band.

In some embodiments, the feedback loop and messages exchanged may beused to indicate an amount of energy received or alternatively oradditionally may indicate an increase or decrease in the amount ofenergy received as compared to previous measurements. In someembodiments, the processor 110 monitors the amount of energy received bythe receiver 104 at certain points in time and controls/optimizes theadaptive load to maximize the power transferred from terminal 123 toterminal 121. In some embodiments, monitoring the amount of energytransferred includes one or both of (i) receiving information from thereceiver 104 (or a component of an electronic device in which thereceiver 104 is located) that indicates an amount of energy received bythe receiver 104 at a certain point in time and (ii) monitoring anamount of energy that remains in the conductive line at terminal 121(instead of having been absorbed by the receiver 104). In someembodiments, both of these monitoring techniques are utilized while, inother embodiments, one or the other of these monitoring techniques isutilized.

In some embodiments, the receiver 104 (i.e., an electronic device thatincludes the receiver 104 as an internally or externally connectedcomponent) may be placed anywhere on top of the charging pad 100 (i.e.,partially or fully covering the conductive line that forms a meanderedpattern on a respective antenna element 120) and the processor 110 willcontinue to monitor the amount of energy transferred and make neededadjustments (e.g., to impedance and/or frequency) to maximize the energytransferred to the receiver 104.

To help illustrate operation of the charging pad 100 and the antennaelements 120 included therein, the transmitting antenna element 120shown in FIG. 3B is divided into two sections: 1) section 125 starts atthe terminal 123 of the antenna element 120 and extends to an edge ofthe receiver 104; and 2) section 127 is formed by the rest of thetransmitting antenna element 120 and the terminal 121. The blocks aredescribed in more detail below with respect to FIG. 3C. It should beunderstood that sections 125 and 127 are functional representations usedfor illustrative purposes, and they are not intended to designate aspecific implementation that partitions an antenna element into separatesections.

Turning now to FIG. 3C, a block diagram of the TX antenna 120 is shown.In some embodiments, an effective impedance value (Z_(effective)),starting from a point that divides sections 125 and 127 and ending atthe TX antenna 120's connection to the adaptive load 106 (e.g., terminal121) will change based on location of the receiver 104 on the TX antenna120 and based on a selected load provided by adaptive load 106 at theterminal 121. In some embodiments, the selected load is optimized by theadaptive load 106 (in conjunction with the processor 110, FIG. 3A) totune Z_(effective) in such a way that the energy transferred betweenterminal 123 and the receiver 104 reaches a maximum (e.g., 75% or moreof energy transmitted by antenna elements of the pad 100 is received bythe RF receiver 104, such as 98%), while energy transfer may also stayat a minimum from terminal 123 to terminal 121 (e.g., less than 25% ofenergy transmitted by antenna elements of the pad 100 is not received bythe RF receiver 104 and ends up reaching terminal 121 or ends up beingreflected back, including as little as 2%).

In embodiments in which an electromechanical switch (e.g., a mechanicalrelay) is used to switch between open and shorted states, moving theswitch from the open to the shorted state (e.g., shorted to a groundplane) for a particular antenna element 120 causes the impedance value,Z_(effective), at a respective terminal 121 for that particular antennaelement 120 to drop to a value close to 0 (alternatively, switching fromthe shorted to the open state causes the impedance value to jump closeto a value close to infinity). In some embodiments, the frequencyadaptation scheme discussed above in reference to FIG. 3A is employed totest various combinations of impedance values and RF signal frequencies,in order to maximize energy transferred to an RF receiver (e.g.,receiver 104, FIGS. 3A-3C). In some embodiments, an integrated circuit(IC or chip) may be used instead of an electromechanical switch as theadaptive load 106. In such embodiments, the adaptive load 106 isconfigured to adjust the impedance value along a range of values, suchas between 0 and infinity. In some embodiments, the IC may be formed byadaptive/reconfigurable RF active and/or passive elements (e.g.,transistors and transmission lines) that are controlled by firmware ofthe IC (and/or firmware executing on the CPU 110 that controls operationof the IC). In some embodiments, the impedance produced by the IC, andcontrolled through firmware and based on information from the feedbackloop (discussed above in reference to FIG. 3A), may be changed to coverany load values selected from a Smith Chart (or the IC may be designedto produce certain loads covering a portion of values form the SmithChart). In some embodiments, this IC is distinct from the RF powertransmitter integrated circuit 160 (FIG. 1B) that is used to manageoverall operation of the pad 100, and this other IC is also incommunication with the RF power transmitter integrated circuit 160 toallow the circuit 160 to control adjustments to impedance values. ASmith Chart may be sampled and stored in a memory (e.g., as a lookuptable) that is accessible by the processor 110, and the processor 110may perform lookups using the stored Smith Chart to determine variousimpedance values to test. For example, the integrated circuit may beconfigured to select a predetermined number of complex values (e.g., 5jto 10j, 100+0j, or 0+50j, etc.) for the impedance value to test incombination with various RF transmission frequencies, in order to locatea combination of values that optimizes energy transferred to thereceiver 104 (examples of maximized energy transfer are discussedabove).

In some other embodiments, a transmitter or charging pad with more thanone antenna elements 120 of FIG. 1B with one adaptive load 106 may beconfigured to operate in two or more distinct frequency bandsrespectively at the same time. For example, a first antenna elementoperates at a first frequency or frequency band, a second antennaelement operates at a second frequency or frequency band, and a thirdantenna element operates at a third frequency or frequency band, and afourth antenna element operates at a fourth frequency or frequency band,and the four frequency bands are distinct from each other. A transmitterwith two or more antenna elements 120 therefore can be used as amulti-band transmitter.

FIG. 3D is a block diagram of a simplified circuit that illustratesenergy flow within sections of an antenna element that is transmittingan RF signal, in accordance with some embodiments. The references topart1 and part2 in FIG. 3D refer to sections illustrated in FIGS. 3B and3C, in particular, part1 corresponds to section 125 and part2corresponds to section 127.

As shown in FIG. 3D, the effective impedance (Z_(effective)) for atransmitting antenna element 120 is formed by the portion of theconductive line that is after the receiver 104 (which, in someembodiments, forms a meandered line pattern as discussed in more detailbelow) and the adaptive load (labelled to as section 127 in FIGS. 3B and3C). In some embodiments, by optimizing, the load Z_(effective) will betuned so the energy transferred from PA to the receiver 104 ismaximized; and, the energy remaining in the conductive line by the timeit reaches the adaptive load is minimized (as discussed above).

FIG. 4 is a schematic of an antenna element with two terminals, inaccordance with some embodiments. As shown in FIG. 4, an input or firstterminal of the antenna element 120 (also described as terminal 123 inreference to FIGS. 3B-3D above) is connected with a power amplifier 108and an output or second terminal (also described as terminal 121 inreference to FIGS. 3B-3D above) is connected with a load pick 106 thatallows for configuring an adaptive load. Stated another way, in someembodiments, the antenna element 120 is fed by the power amplifier 108from the first terminal and the antenna element 120 is also terminatedat a second terminal at an adaptive load (for example, the mechanicalrelay that switches between shorted and open states).

In some embodiments, the charging pad 100 (FIG. 3A) is made ofsingle-layer or multi-layer copper antenna elements 120 with conductivelines that form a meandered line pattern. In some embodiments, each ofthese layers has a solid ground plane as one of its layers (e.g., abottom layer). One example of a solid ground plane is shown and labelledfor the transmitting antenna element shown in FIG. 4.

In some embodiments, the RF charging pad 100 (and individual antennaelements 120 included therein) is embedded in a consumer electronicdevice, such as a projector, a laptop, or a digital media player (suchas a networked streaming media player, e.g. a ROKU device, that isconnected to a television for viewing streaming television shows andother content). For example, by embedding the RF charging pad 100 in aconsumer electronic device, a user is able to simply place a peripheraldevice, such as a remote for a projector or a streaming media player(e.g., the remote for the projector or streaming media player includes arespective receiver 104, such as the example structures for a receiver104 shown in FIGS. 7A-7D), on top of the projector or the streamingmedia player and the charging pad 100 included therein will be able totransmit energy to a receiver 104 that is internally or externallyconnected to the remote, which energy is then harvested by the receiver104 for charging of the remote.

In some embodiments, the RF charging pad 100 may be included in a USBdongle as a standalone charging device on which a device to be chargedis placed. In some embodiments, the antenna elements 120 may be placednear a top surface, side surfaces, and/or a bottom surface of the USBdongle, so that a device to be charged may be placed at variouspositions that contact the USB dongle (e.g., a headphone that is beingcharged might sit on top of, underneath, or hang over the USB dongle andwould still be able to receive RF transmissions from the embedded RFcharging pad 100).

In some embodiments, the RF charging pad 100 is integrated intofurniture, such as desks, chairs, countertops, etc., thus allowing usersto easily charge their devices (e.g., devices that includes respectivereceivers 104 as internally or externally connected components) bysimply placing them on top of a surface that includes an integrated RFcharging pad 100.

Turning now to FIG. 5, a flowchart of a method 500 of charging anelectronic device through radio frequency (RF) power transmission isprovided. Initially, a transmitter is provided 502 that includes atleast one RF antenna (e.g., antenna element 120, FIGS. 3B-3D and 4) fortransmitting one or more RF signals or waves, i.e., an antenna designedto and capable of transmitting RF electromagnetic waves. In someembodiments, an array of RF antenna elements 120 are arranged adjacentto one another in a single plane, in a stack, or in a combination ofthereof, thus forming an RF charging pad 100. In some embodiments, theRF antenna elements 120 each include an antenna input terminal (e.g.,the first terminal 123 discussed above in reference to FIG. 4) and anantenna output terminal (e.g., the second terminal 121 discussed abovein reference to FIG. 4).

In some embodiments, a receiver (e.g., receiver 104, FIGS. 3A-3D) isalso provided 504. The receiver also includes one or more RF antennasfor receiving RF signals 310. In some embodiments, the receiver includesat least one rectenna that converts 318 the one or more RF signals intousable power to charge a device that includes the receiver 104 as aninternally or externally connected component. In use, the receiver 104is placed 506 within a near-field radio frequency distance to the atleast one antenna. For example, the receiver may be placed on top of theat least one RF antenna or on top of a surface that is adjacent to theat least one RF antenna, such as a surface of a charging pad 100.

One or more RF signals are then transmitted 508 via at the least one RFantenna. The system is then monitored 512/514 to determine the amount ofenergy that is transferred via the one or more RF signals from the atleast one antenna to a RF receiver (as is also discussed above). In someembodiments, this monitoring 512 occurs at the transmitter, while inother embodiments the monitoring 514 occurs at the receiver which sendsdata back to the transmitter via a back channel (e.g., over a wirelessdata connection using WIFI or BLUETOOTH). In some embodiments, thetransmitter and the receiver exchange messages via the back channel, andthese messages may indicate energy transmitted and/or received, in orderto inform the adjustments made at step 516.

In some embodiments, a characteristic of the transmitter is adaptivelyadjusted at step 516 to attempt to optimize the amount of energy that istransferred from the at least one RF antenna to the receiver. In someembodiments, this characteristic is a frequency of the one or more RFsignals and/or an impedance of the transmitter. In some embodiments, theimpedance of the transmitter is the impedance of the adjustable load.Also in some embodiments, the at least one processor is also configuredto control the impedance of the adaptive load. Additional details andexamples regarding impedance and frequency adjustments are providedabove.

In some embodiments, the transmitter includes a power input configuredto be electrically coupled to a power source, and at least one processor(e.g., processor 110, FIGS. 3A-3B) configured to control at least oneelectrical signal sent to the antenna. In some embodiments, the at leastone processor is also configured to control the frequency of the atleast one signal sent to the antenna.

In some embodiments, the transmitter further comprises a power amplifierelectrically coupled between the power input and the antenna inputterminal (e.g., PA 108, FIGS. 3A, 3B, 3D, and 4). Some embodiments alsoinclude an adaptive load electrically coupled to the antenna outputterminal (e.g., terminal 121, FIGS. 3A-3C and 4). In some embodiments,the at least one processor dynamically adjusts the impedance of theadaptive load based on the monitored amount of energy that istransferred from the at least one antenna to the RF receiver. In someembodiments, the at least one processor simultaneously controls thefrequency of the at least one signal sent to the antenna.

In some embodiments, each RF antenna of the transmitter includes: aconductive line forming a meandered line pattern, a first terminal(e.g., terminal 123) at a first end of the conductive line for receivingcurrent that flows through the conductive line at a frequency controlledby one or more processors, and a second terminal (e.g., terminal 121),distinct from the first terminal, at a second end of the conductiveline, the second terminal coupled to a component (e.g., adaptive load106) controlled by the one or more processors and that allows formodifying an impedance value of the conductive line. In someembodiments, the conductive line is disposed on or within a firstantenna layer of a multi-layered substrate. Also in some embodiments, asecond antenna is disposed on or within a second antenna layer of themulti-layered substrate. Finally, some embodiments also provide a groundplane disposed on or within a ground plane layer of the multi-layeredsubstrate.

In some embodiments, the method described above in reference to FIG. 5is performed in conjunction with the methods described below inreference to FIGS. 9A-9B, 10, and 11A-11E. For example, the operationsof modifying/adjusting impedance values are performed after determiningwhich antenna zones (the “determined antenna zones”) to use fortransmitting wireless power to a receiver, and then impedance values atthe determined antenna zones are adjusted to ensure that a maximumamount of power is transferred wirelessly to the receiver by antennaswithin the determined antenna zones.

FIGS. 6A-6E are schematics showing various configurations for individualantenna elements within an RF charging pad, in accordance with someembodiments. As shown in FIGS. 6A-6E, an RF charging pad 100 (FIG. 3A)may include antenna elements 120 that are made using differentstructures.

For example, FIGS. 6A-6B show examples of structures for an antennaelement 120 that includes multiple layers that each include conductivelines formed into meandered line patterns. The conductive lines at eachrespective layer may have the same (FIG. 6B) or different (FIG. 6A)widths (or lengths, or trace gauges, or patterns, spaces between eachtrace, etc.) relative to other conductive lines within a multi-layerantenna element 120. In some embodiments, the meandered line patternsmay be designed with variable lengths and/or widths at differentlocations of the pad 100 (or an individual antenna element 120), and themeandered line patterns may be printed on more than one substrate of anindividual antenna element 120 or of the pad 100. These configurationsof meandered line patterns allow for more degrees of freedom and,therefore, more complex antenna structures may be built that allow forwider operating bandwidths and/or coupling ranges of individual antennaelements 120 and the RF charging pad 100.

Additional example structures are provided in FIGS. 6C-6E: FIG. 6C showsan example of a structure for an antenna element 120 that includesmultiple layers of conductive lines forming meandered line patterns thatalso have sliding coverage (in some embodiments, respective meanderedline patterns may be placed in different substrates with just a portionof a first meandered line pattern of a respective substrate overlappingthe a second meandered line pattern of a different substrate (i.e.,sliding coverage), and this configuration helps to extend coveragethroughout width of the antenna structure); FIG. 6D shows an example ofa structure for an antenna element 120 that includes a conductive linehaving different lengths at each turn within the meandered line pattern(in some embodiments, using different lengths at each turn helps toextend coupling range of the antenna element 120 and/or helps add to theoperating bandwidth of the RF charging pad 100); and FIG. 6E shows anexample of a structure for an antenna element 120 that includes aconductive line that forms two adjacent meandered line patterns (in someembodiments, having a conductive line that forms two adjacent meanderedline patterns helps to extend width of the antenna element 120). All ofthese examples are non-limiting and any number of combinations andmulti-layered structures are possible using the example structuresdescribed above.

FIGS. 7A-7D are schematics of an antenna element for an RF receiver, inaccordance with some embodiments. In particular FIGS. 7A-7D showexamples of structures for RF receivers (e.g., receiver 104, FIGS. 3A-3Dand 4), including: (i) a receiver with a conductive line that formsmeandered line patterns (the conductive line may or may not be backed bysolid ground plane or reflector), as shown in FIGS. 7A (single-polarityreceiver) and 7B (dual-polarity receiver). FIGS. 7C-7D show additionalexamples of structures for an RF receiver with dual-polarity and aconductive line that forms a meandered line pattern. Each of thestructures shown in FIGS. 7A-7D may be used to provide differentcoupling ranges, coupling orientations, and/or bandwidth for arespective RF receiver. As a non-limiting example, when the antennaelement shown in FIG. 7A is used in a receiver, very small receivers maybe designed/built that only couple to the pad 100 in one direction. Asanother non-limiting example, when the antenna elements shown in FIGS.7B-7D are used in a receiver, the receiver is then able to couple to thepad 100 in any orientation.

Other examples and descriptions of meandered line patterns for antennaelements are provided below. FIG. 8 is a schematic of an RF charging padwith a plurality of transmitting antenna elements (unit cells) that forma larger RF charging/transmitting pad, in accordance with someembodiments. In some embodiments, the RF charging pad 100 is formed asan array of adjacent antenna elements 120 (the distance between cellsmay be optimized for the best coverage). In some embodiments, when areceiver is placed in an area/gap that is between adjacent antennaelements 120, attempts to optimize energy transfer (e.g., in accordancewith the adaptation scheme discussed above in reference to FIG. 3A) maynot result in increased energy transfer above an acceptable thresholdlevel (e.g., 75% or more). As such, in these circumstances, adjacentantenna elements may both be configured to transmit RF waves at fullpower at the same time to transfer additional energy to a receiver thatis placed on a surface of the RF charging pad, and at a location that isbetween adjacent antenna elements 120.

As one possible configuration in accordance with some embodiments, port(or terminal) group #1 (FIG. 8) supplies power, port (or terminal)groups #2 and #3 provide adaptive loads (e.g., an electromechanicalrelay moving between short-circuit and open-circuit states). As anotherexample of a suitable configuration, port (or terminal) groups #1, #2and #3 may also be used to supply power via a power amplifier to thecharging pad 100 (at the same time or with one group at a time beingswitched when necessary).

In some embodiments, each transmitting antenna element 120 of the RFcharging pad 100 forms a separate antenna zone which is controlled by afeeding (PA) terminal and one or more terminals to support adaptiveload(s), as explained in detail above. In some embodiments, feedbackfrom the receiver helps determine the antenna zone on top of which thereceiver is placed, and this determination activates that zone (e.g.,using the switch 295, FIG. 1C). In circumstances in which the receiveris placed between two or more zones (e.g., at an area/gap that isbetween adjacent antenna elements 120), additional adjacent zones mightbe activated to ensure sufficient transfer of energy to the receiver.Additional details regarding determining zones to use for transmittingwireless power to the receiver are provided below in reference to FIGS.9A-9B, 10, and 11A-11E.

FIGS. 9A-9B are flow diagrams showing a method 900 of selectivelyactivating one or more antenna zones (e.g., activating the antennasassociated therewith) in a near-field charging pad, in accordance withsome embodiments. Operations of the method 900 are performed by anear-field charging pad (e.g. RF charging pad 100, FIGS. 1B and 2A) orby one or more components thereof (e.g., those described above withreference to FIGS. 1A-1B and 2A). In some embodiments, the method 900corresponds to instructions stored in a computer memory orcomputer-readable storage medium (e.g., memory 206 of the RF chargingpad 100, FIG. 2A).

The near-field charging pad includes one or more processors (e.g., CPU202, FIG. 1B), a wireless communication component (e.g., communicationcomponent(s) 204, FIGS. 1A and 2A), and a plurality of antenna zones(e.g., antenna zones 290-1 and 290-N, FIG. 1B) that each respectivelyinclude at least one antenna element (e.g., one of antennas 210, whichmay be one of the antennas 120 described in reference to FIGS. 3A-6E)(902). In some embodiments, the near-field charging pad includesdistinct antennas (or unit cells including antennas, also referred toherein as antenna elements) that are each included in respective antennazones. For example, as shown in FIG. 1B, an antenna zone 290-1 includesan antenna 210-A. In another example, as is also shown in FIG. 1B, anantenna zone 290-N includes multiple antennas. The antenna zones mayalso be referred to as antenna groups, such that the near-field chargingpad includes a plurality of antenna zones or groups, and each respectivezone/group includes at least one of the distinct antenna elements (e.g.,at least one antenna 210). It should be noted that an antenna zone caninclude any number of antennas, and that the numbers of antennasassociated with a particular antenna zone may be modified or adjusted(e.g., the CPU subsystem 170 of RF power transmitter integrated circuit160 responsible for managing operations of the near-field charging pad100 dynamically defines each antenna zone at various points in time, asis discussed in more detail below). In some embodiments, each antennazone includes a same number of antennas.

In some embodiments, the one or more processors are a component of asingle integrated circuit (e.g., RF power transmitter integrated circuit160, FIG. 1B) that is used to control operation of the near-fieldcharging pad. In some embodiments, the one or more processors and/or thewireless communication component of the near-field charging pad is/areexternal to the near-field charging pad, such as one or more processorsof a device in which the near-field charging pad is embedded. In someembodiments, the wireless communication component is a radio transceiver(e.g., a BLUETOOTH radio, WI-FI radio, or the like for exchangingcommunication signals with wireless power receivers).

In some embodiments, the method includes establishing (904) one or moredevice detection thresholds during a calibration process for thenear-field charging pad. In some instances, the calibration process isperformed after manufacturing the near-field charging pad and includesplacing devices of various types (e.g., smartphones, tablets, laptops,connected devices, etc.) on the near-field charging pad and thenmeasuring a minimum amount of reflected power detected at an antennazone while transmitting test power transmission signals to the devicesof various types. In some instances, a first device-specific thresholdis established at a value corresponding to 5% or less of the minimumamount of reflected power. In some embodiments, a second device-specificthreshold is also established so that if no one antenna zone is able tosatisfy the first threshold (e.g., because the wireless power receiveris located at a border between antenna zones), then the second, higherthreshold may be used to locate more than one antenna zone to use fortransmitting power to the wireless power receiver (as discussed in moredetail below). In some embodiments, multiple first and seconddevice-specific detection thresholds are established for each type ofdevice of the various types, and these multiple first and seconddevice-specific detection thresholds may be stored in a memoryassociated with the RF power transmitter integrated circuit 160 (e.g.,memory 206, FIG. 2A).

The method 900 also includes detecting (906), via the wirelesscommunication component, that a wireless power receiver is within athreshold distance of the near-field charging pad. In some instances,the detecting may occur after the near-field charging pad is turned on(e.g., powered up). In these instances, the near-field charging padscans an area around the near-field charging pad (e.g., to scan forwireless power receivers that are located within the threshold distance,e.g., within 1-1.5 meters, away from the NF charging pad 100) todetermine whether any wireless power receivers are within the thresholddistance of the NF charging pad 100. The near-field charging pad may usethe wireless communication component (e.g., communication component(s)204, FIG. 2A, such as a Bluetooth radio) to conduct the scanning forsignals broadcasted by wireless communication components associated withwireless power receivers (e.g., communication component 254, FIG. 2B).In some embodiments, the device detection threshold is selected (fromamong the multiple first and second device detection threshold discussedabove) by the one or more processors after detecting the wireless powerreceiver within the threshold distance of the near-field charging pad.For example, a wireless communication component of the wireless powerreceiver is used to provide information to the near-field charging padthat identifies the type of device, such as a BLUETOOTH or BLUETOOTH lowenergy advertisement signal that includes this information. In someembodiments, to save energy and prolong life of the near-field chargingpad and its components, no wireless power is transmitted (and the devicedetection and antenna selection algorithms discussion herein are notinitiated) until a wireless power receiver is detected within thethreshold distance of the near-field charging pad.

In some embodiments, the detecting 906 also includes performing anauthorization handshake (e.g., using the secure element modules 234 and282, FIGS. 2A and 2B) to ensure that the wireless power receiver isauthorized to receive wirelessly delivered power from the near-fieldcharging pad and the method only proceeds to operation 908 if it isdetermined that the wireless power receiver is so authorized. In thisway, the near-field charging pad ensures that only authorized wirelesspower receivers are able to receive wirelessly delivered power and thatno device is able to leech power that is transmitted by the near-fieldcharging pad.

The method 900 further includes, in response to detecting that thewireless power receiver is within the threshold distance of thenear-field charging pad, determining (912) whether the wireless powerreceiver has been placed on the near-field charging pad. In someembodiments, this is accomplished by transmitting (908) test powertransmission signals using each of the plurality of antenna zones andmonitoring (910) an amount of reflected power at the near-field chargingpad while transmitting the test power transmission signals.

In some embodiments, if the amount of reflected power does not satisfythe device detection threshold (e.g., the amount of reflected power isgreater than 20% of power transmitted with the test power transmissionsignals), then a determination is made that the wireless power receiverhas not been placed on the surface of the near-field charging pad(912—No). In accordance with this determination, the near-field chargingpad continues to transmit test power transmission signals using each ofthe plurality of antenna zones at step 914 (i.e., proceed to step 908).In some embodiments, the operations at 908 and 910 are performed untilit is determined that the device detection threshold has been satisfied.

In some embodiments, the amount of reflected power is measured at eachantenna zone of the plurality of antenna zones (e.g., each antenna zonemay be associated with a respective ADC/DAC/Power Detector, such as theone shown in FIG. 1B) while, in other embodiments, the amount ofreflected power may be measured using a single component of the RF powertransmitter integrated circuit 160 (e.g., the ADC/DAC/Power Detector).When the amount of reflected power satisfies the device detectionthreshold (912—Yes), the wireless power receiver is determined to havebeen placed on the near-field charging pad. For example, the amount ofreflected power may satisfy the device detection threshold when theamount of reflected power is 20% or less than amount of powertransmitted with the test power transmission signals. Such a resultindicates that a sufficient amount of the power transmitted with thetest power transmission signals was absorbed/captured by the wirelesspower receiver.

In some embodiments, other types of sensors (e.g., sensors 212, FIG. 2A)are included in or in communication with the near-field charging pad tohelp determine when the wireless power receiver has been placed on thenear-field charging pad. For example, in some embodiments, one or moreoptical sensors (e.g., when light is blocked from a part of the pad,then this may provide an indication that the wireless power receiver hasbeen placed on the pad), one or more vibration sensors (e.g., when avibration is detected at the pad, then this may provide an indicationthat the wireless power receiver has been placed on the pad), one ormore strain gauges (e.g., when a strain level at a surface of the padincreases, this may provide an indication that the wireless powerreceiver has been placed on the surface), one or more thermal sensors(e.g., when a temperature at a surface of the pad increases, this mayprovide an indication that the wireless power receiver has been placedon the surface), and/or one or more weighing sensors (e.g., when anamount of weight measured on the surface of the pad increases, then thismay provide an indication that the wireless power receiver has beenplaced on the surface) are utilized to help make this determination.

In some embodiments, before transmitting the test power transmissionsignals, the method includes determining that the wireless powerreceiver is authorized to receive wirelessly delivered power from thenear-field charging pad. For example, as shown in FIGS. 2A-2B, thewireless power receiver 104 and the near-field charging pad 100 mayinclude secure element modules 282 and 234, respectively, which are usedto perform this authorization process, thereby ensuring that onlyauthorized receivers are able to receive wirelessly delivered power fromthe near-field charging pad.

The method 900 further includes, in accordance with determining that thewireless power receiver has been placed on the near-field charging pad,selectively transmitting (916), by respective antenna elements includedin the plurality of antenna zones, respective test power transmissionsignals with a first set of transmission characteristics. In someembodiments, the selectively or sequentially transmitting is performedusing each antenna zone of the plurality of antenna zones (918).Selectively or sequentially transmitting refers to a process ofselectively activating antenna zones one at a time to cause one or moreantennas associated with individual antenna zones to transmit test powertransmission signals (e.g., the RF power transmitter integrated circuit160 provides one or more control signals to the switch 295 toselectively activate different antenna zones).

Referring now to FIG. 9B, the method 900 further includes determining(920) whether a particular power-delivery parameter associated withtransmission of a respective test power transmission signal (during thesequential or selective transmission operation at 916 and/or 918) by atleast one particular antenna zone of the plurality of antenna zonessatisfies power-delivery criteria (e.g., whether the particularpower-delivery parameter indicates that more than a threshold amount ofpower is transferred to the wireless power receiver by the at least oneparticular antenna zone). In some embodiments, each respectivepower-delivery parameter corresponds to an amount of power received bythe wireless power receiver based on transmission of a respective testpower transmission signal by a respective antenna group of the pluralityof antenna groups.

Upon determining, by the one or more processors, that the particularpower-delivery parameter satisfies the power-delivery criteria(920—Yes), the method further includes transmitting (922) a plurality ofadditional power transmission signals to the wireless power receiverusing the at least one particular antenna zone, where each additionalpower transmission signal of the plurality is transmitted with a secondset of transmission characteristics, distinct from the first set. Insome embodiments, the second set of transmission characteristics isdetermined by adjusting at least one characteristic in the first set oftransmission characteristics to increase an amount of power that istransferred by the particular antenna group to the wireless powerreceiver. Moreover, in some embodiments, the at least one adjustedcharacteristic is a frequency or impedance value (and the frequency andimpedance value may be adjusted using the adaptation scheme discussedabove).

The test power transmission signals discussed above are used to helpdetermine which antenna zones to use for delivering wireless power tothe wireless power receiver. In some embodiments, these test powertransmission signals are not used by the wireless power receiver toprovide power or charge to the wireless power receiver, or a deviceassociated therewith. Instead, the plurality of additional powertransmission signals is used to provide power or charge to the wirelesspower receiver. In this way, the near-field charging pad is able topreserve resources during a device detection stage (e.g., whiletransmitting the test power transmission signals) until a suitableantenna zone is located for transmitting the plurality of additionalpower transmission signals. As such, the method 900 is able to locate aposition of the wireless power receiver using test signals (i.e., thetest power transmission signals with the first set of transmissioncharacteristics) and then transmit using antenna from an antenna zonethat is best-suited to provide power transmission signals given theposition of the wireless power receiver on the near-field charging pad.As discussed in more detail below with reference to FIG. 10, thisprocess may include a coarse search for antenna zones (e.g., the coarsesearch may include the operations 908-918) and a finer search forantenna zones (e.g., the finer search may include operations 920-934).

In some embodiments, a power control process (FIG. 11E) is also used tohelp optimize a level of power delivered to the wireless power receiverusing the selected antenna zones (e.g., power control may be performedafter operations 922, 930, or 934 to tune transmission of wireless powerusing the antenna zones that were selected during the method 900). As apart of the power control process, the near-field charging pad may,while transmitting the additional plurality of power transmissionsignals, adjust at least one characteristic in the second set oftransmission characteristics based on information, received from thewireless power receiver, which is used to determine a level of powerthat is wirelessly delivered to the wireless power receiver by thenear-field charging pad.

Returning back to operation 920, in response to determining that none ofthe power-delivery parameters associated with transmission of the testpower transmission signals during the sequential or selectivetransmission operation(s) at 916 (and optionally 918) satisfy thepower-delivery criteria (920—No), the method 900 further includesselecting (924) two or more antenna zones (also referred tointerchangeably herein as two+ antenna zones) based on their associatedrespective power-delivery parameters. This may arise when the wirelesspower receiver is not centered over any particular antenna zone (e.g.,the receiver may be over more than one antenna zone). For example, thetwo or more antenna zones that transferred the highest amount of powerto the wireless power receiver during the sequential or selectivetransmission operation at 916 (and optionally 918) based on theirrespective power-delivery parameters are selected at operation 924. Inthis way, in some embodiments, a finer search for the most efficientantenna zone is started by selecting the two or more antenna zones thatmost efficiently transmitted power to the wireless power receiver duringthe operations at 916/918 based on their respective association withpower-delivery parameters that is higher than the power-deliveryparameters for other antenna zones. In these embodiments, a respectivepower-delivery parameter may be monitored (in conjunction withoperations 916/918) for each antenna zone and these power-deliveryparameters are then compared to determine which of the plurality ofantenna zones to select as the two or more antenna zones to use fortransmission of wireless power.

After selecting the two or more antenna zones, the method furtherincludes: (i) updating the test power transmission signals by modifyingat least one characteristic of the test power transmission signals(e.g., frequency, impedance, amplitude, phase, gain, etc.), based on theprevious transmissions (e.g., based on feedback received from thewireless power receiver regarding a level of power receive by thewireless power receiver or based on an amount of reflected powermeasured at each antenna group after the transmission), and (ii)transmitting (926) the updated test power transmission signals usingeach of the two or more antenna zones (e.g., the RF power transmitterintegrated circuit 160 may provide one or more control signals to theswitch 295 to activate the two or more antenna zones).

The method 900 further includes determining (928) whether a particularpower-delivery parameter associated with transmission of an updatedrespective test power transmission signal by a zone of the two or moreantenna zones satisfies power-delivery criteria. In response todetermining that the particular power-delivery parameter associated withtransmission of the updated respective test power transmission signal bythe zone of the two or more antenna zones satisfies the power-deliverycriteria (928—Yes), the method 900 further includes transmitting (930) aplurality of additional power transmission signals to the wireless powerreceiver using the zone of the two or more antenna zones, where eachadditional power transmission signal of the plurality is transmittedwith a second set of transmission characteristics, distinct from thefirst set (e.g., the RF power transmitter integrated circuit 160 mayprovide a control signal to the switch 295). The plurality of additionalpower transmission signals is used to wirelessly deliver power to thewireless power receiver (or an electronic device coupled with thewireless power receiver).

In some embodiments, the determination that the particularpower-delivery parameter satisfies the power-delivery criteria atoperations 920 and 928 may include determining that respectivepower-delivery parameters (associated with the at least one particularzone and/or the zone of the two or more antenna zones) indicates that afirst threshold amount of power is transferred to the wireless powerreceiver. If such a determination is made at operation 928, thisindicates that the zone is the only antenna zone of the two or moreantenna zones having a respective power-delivery parameter thatindicates that the first threshold amount of power is transferred to thewireless power receiver by the zone in conjunction with operation 926.

In some embodiments, the first threshold amount of power corresponds toan amount of power received by the wireless power receiver (in somecircumstances, the first threshold amount of power could alternativelycorrespond to an amount of reflected power detected at the near-fieldcharging pad). As discussed above, in some embodiments, a calibrationprocess is performed after manufacturing the near-field charging pad andincludes placing devices of various types (e.g., smartphones, tablets,laptops, connected devices, etc., that are each coupled with wirelesspower receivers) on the near-field charging pad and then measuring amaximum amount of power received at the receiver (or device coupledthereto) after transmission of the test signal by an antenna group tothe devices of various types. In some instances, the first threshold isestablished at a value corresponding to a percentage of the maximumamount of received power (e.g., approximately 85% or more of powertransmitted by a particular antenna zone is received by the receiver).

As explained above, during embodiments of the calibration process, asecond threshold is also established so that if no one antenna zone isable to satisfy the first threshold (e.g., because the wireless powerreceiver may be located at a border between antenna groups) then thesecond threshold may be utilized to locate more than one antenna zone totransmit wireless power to the wireless power receiver (as discussedbelow). This second threshold may be another percentage of the maximumamount of reflected power that is measured during the calibrationprocess (e.g., 65%). In some embodiments, the first and secondthresholds are determined as respective device-specific first and secondthresholds for each of the devices undergoing the calibration process.

In some embodiments, the method 900 includes determining (928—No) that(i) no antenna zone of the two or more antenna zones is transferring thefirst threshold amount of power to the wireless power receiver and (ii)an additional power-delivery parameter associated with an additionalantenna zone of the two or more antenna zones satisfies thepower-delivery criteria. For example, a respective power-deliveryparameter indicates that a first amount of power transferred to thewireless power receiver by the zone of the two or more zones is above asecond threshold amount of power and below the first threshold amount ofpower, and the additional power-delivery parameter also indicates that asecond amount of power transferred to the wireless power receiver by theadditional antenna zone is above the second threshold amount of powerand below the first threshold amount of power. In other words, if noantenna zone of the two or more antenna zones is able to transfer enoughpower to the wireless power receiver to satisfy the first thresholdamount of power, then the method proceeds to determine whether two ofthe antenna groups transferred enough power to the wireless powerreceiver to satisfy a second, lower threshold amount of power. Forexample, the wireless power receiver may be located at a border betweentwo antenna groups, so no one antenna group is able to satisfy the firstthreshold, but these two antenna groups may be able to each individuallysatisfy the second threshold amount of power.

Upon determining, by the one or more processors of the near-fieldcharging pad, that the power-delivery parameters associated withtransmission of the updated test power transmission signals by the twoor more antennas zones satisfy the power-delivery criteria (932—Yes),the method further includes transmitting (934) a plurality of additionalpower transmission signals to the wireless power receiver using the twoor more antenna zones. Such a situation may arise when the wirelesspower receiver is placed between two adjacent antenna zones. In someembodiments, the two or more antenna zones each simultaneously transmitthe additional plurality of power transmission signals to provide powerto the wireless power receiver.

As is also shown in FIG. 9B, if the two or more zones do not havepower-delivery parameters that satisfy the power-delivery criteria(932—No), then the method 900 returns to operation 906 to startsearching for the receiver (or a different receiver again), as noantenna zones were located that could efficiently transfer wirelesspower to the receiver. In some embodiments, the method 900 mayalternatively return to operation 924 to begin transmitting test powertransmission signals with different characteristics to determine ifthose characteristics are able to then allow the two or more antennazones to deliver enough wireless power to the receiver to satisfy thepower-delivery criteria. In some embodiments, the method 900 returns tooperation 924 a predetermined number of times (e.g., 2) and, if the twoor more zones still do not have power-delivery parameters that satisfythe power-delivery criteria, then the method at that point returns tooperation 906 to begin searching for new receivers.

In some embodiments, after the method 900 successfully locates antennazones to use for wirelessly delivering power to the receiver (e.g., atoperations 922, 930, and 934) then the method 900 returns to operation906 to being search for new receivers. The near-field charging pad, insome embodiments, is capable of simultaneously delivering wireless powerto multiple receivers at any particular point in time and, therefore,iterating through the method 900 again allows the near-field chargingpad to appropriately determine which antenna zones to use fortransmission of wireless power to each of these multiple receivers.

In some embodiments, information used to determine respectivepower-delivery parameters for each of the antenna zones of thenear-field charging pad is provided to the near-field charging pad bythe wireless power receiver via the wireless communication component ofthe near-field charging pad (e.g., the receiver transmits informationthat is used to determine an amount of power received by the receiverfrom the test power transmission signals discussed above). In someembodiments, this information is sent via a connection between thewireless communication component of the near-field charging pad and thewireless power receiver, and the connection is established upondetermining that the wireless power receiver has been placed on thenear-field charging pad.

Additionally, in some embodiments, the near-field charging paddynamically creates or defines antenna zones. For example, withreference to FIG. 1B, the near-field charging pad may define a firstantenna zone 290-1 to include a single antenna 210-A and may defineanother antenna zone 290-N to include more than one antenna 210. In someembodiments, at various phases of the method 900 discussed above,antenna zones may be redefined. For example, in accordance with thedetermination that the two or more antenna zones do not havepower-delivery parameters that satisfy the power-delivery criteria(932-No), the near-field charging pad may redefine the antenna zones toeach include multiple antennas (instead of having each antenna zoneinclude a single antenna). In this way, the method 900 is able todynamically define antenna zones to help ensure that an appropriateantenna zone is located that may be used to transmit wireless power to areceiver that has been placed on the near-field charging pad.

FIG. 10 is an overview showing a process 1000 of selectively activatingone or more antenna groups in a near-field charging pad, in accordancewith some embodiments. Some of the operations in process 1000 correspondto or supplement the operations describe above in reference to method900 of FIGS. 9A-9B. As shown in FIG. 10, the process 1000 begins with anear-field charging pad (e.g., RF charging pad 100, FIGS. 1A-1B and 2A)detecting (1002) a wireless power receiver (e.g., wireless powerreceiver 104, FIG. 12B) in range and subsequently on the near-fieldcharging pad (operation 1002 corresponds to operations 906 to 912—Yes inFIG. 9A). The process 1000 further includes performing (1004) a coarsesearch, performing (1006) a fine search, and executing (1008) a powercontrol routine. Each step in the process 1000 is described in furtherdetail below with reference to FIGS. 11A-11E. It should be noted thatthe process 1000, in some embodiments, begins with the near-fieldcharging pad detecting (1002) a wireless power receiver on thenear-field charging pad and subsequently in range of the near-fieldcharging pad.

FIG. 11A is a flowchart detailing a process 1002 for detecting awireless power receiver in range and subsequently on the near-fieldcharging pad (or in some embodiments, on the near-field charging pad andsubsequently in range of the near-field charging pad). The process 1002includes enabling the near-field charging pad (1102), i.e., powering onthe near-field charging pad. Thereafter, the near-field charging padscans (1104) for wireless power receivers and detects (1106) a wirelesspower receiver in range based, at least in part, on a received signalstrength indicator (RSSI). To obtain the RSSI, the near-field chargingpad may use a wireless communication component (e.g., communicationcomponent(s) 204, FIG. 2A, such as a Bluetooth radio) to scan forsignals broadcasted by wireless communication components associated withwireless power receivers (e.g., a Bluetooth advertisement signal).Detecting a wireless power receiver in range of the near-field chargingpad is discussed in further detail above with reference to operation 906of the method 900.

Next, the near-field charging pad detects (1108) a wireless powerreceiver on the near-field charging pad. In some embodiments, thenear-field charging pad establishes that the wireless power receiver ison the near-field charging pad using the processes discussed above inreference to operations 908-914 until it is determined that the wirelesspower receiver has been placed on the near-field charging pad. In someembodiments, operation (1108) occurs before operation (1102).

Continuing, the near-field charging pad establishes (1110) acommunication channel with the wireless power receiver in response todetecting the wireless power receiver on the near-field charging pad.

Turning now to FIG. 11B, the method proceeds to process 1004 in whichthe near-field charging pad performs a coarse search (1004). Inperforming the coarse search 1004, the near-field charging pad begins byenabling (1122) power for an antenna zone (e.g., antenna zone 290-1,FIG. 1B). In some embodiments, enabling power for the antenna zoneincludes transmitting, by an antenna element included in the antennazone (e.g., after the RF power transmitter integrated circuit 160provides one or more control signals to the switch 295 to activate theantenna zone), test power transmission signals with a first set oftransmission characteristics (e.g., phase, gain, direction, amplitude,polarization, and/or frequency). Transmitting test power transmissionsignals is discussed in further detail above with reference to steps916-918 of the method 900.

Continuing with the coarse search 1004, the near-field charging padrecords (1124) an amount of power received by the wireless powerreceiver (the “reported power”). In some embodiments, the reported poweris communicated to the near-field charging pad by the wireless powerreceiver via the communication channel that was established at operation1110.

The near-field charging pad repeats (1126) steps (1122) and (1124) abovefor all antenna zones that have been defined for the near-field chargingpad (e.g., RF power transmitter integrated circuit 160 provides one ormore control signals to the switch 295 to selectively activate all theantenna zones). Thereafter, in some embodiments, the near-field chargingpad selects (1128) a set of antenna zones based on the reported power(e.g., 2 or 3 zones, or some greater or lesser number, depending on thecircumstances) and a configured threshold (e.g., power-deliverycriteria). For ease of discussion, each antenna zone in the set includesa single antenna 210 (e.g., antenna zone 290-1, FIG. 1B). However, itshould be understood that instead of selecting a set of antenna zones,the near-field charging pad could also select a single antenna zone thatincludes multiple antennas 210. For example, as shown in FIG. 1B, theantenna zone 290-N includes multiple antennas 210. In addition, eachantenna zone in the set could also include multiple antennas, dependingon the circumstances.

Turning now to FIG. 11C, after selecting the set of antenna zones basedon the reported power, the near-field charging pad performs the finesearch process (1006). In some embodiments, the fine search 1006 is usedto determine which antenna zone(s) is/are best suited to wirelesslydelivery power to the wireless power receiver, based on a location ofthe wireless power receiver on the near-field charging pad. Inperforming the fine search (1006), the near-field charging pad selects(1132) at least one antenna zone from the set of antenna zones selectedusing the coarse search, and for the at least one antenna zone, thenear-field charging pad sweeps (1134) across available frequenciesand/or impedances (i.e., tunes transmission of power transmissionsignals by the at least one antenna zone). Thereafter, the near-fieldcharging pad records (1136) those characteristics that result inmaximizing an amount of received power reported by the wireless powerreceiver. In some embodiments, operations 1134 and 1136 are repeated foreach antenna zone in the set of antenna zones (1138) and the near-fieldcharging pad selects (1140) an antenna zone (Z1) that delivers a maximumamount of power to the wireless power receiver. In addition, thenear-field charging pad also records the frequency (and othertransmission characteristics) and a relay position by antenna zone Z1 toachieve the delivery of the maximum amount of power to the wirelesspower receiver.

In some circumstances or situations, the amount of power delivered tothe wireless power receiver by the antenna zone Z1 does not meet athreshold amount of power. In these circumstances or situations, thenear-field charging pad performs an adjacent zone search (1007), whichis illustrated in FIG. 11D. In some embodiments, the adjacent zonesearch 1007 is used to identify one or more adjacent zones to theselected antenna zone Z1 that may be activated (e.g., the RF powertransmitter integrated circuit 160 provides one or more control signalsto the switch 295) in order to increase an amount of power delivered tothe wireless power receiver. For example, this may occur when thewireless power receiver is located at a border between adjacent antennazones of the near-field charging pad (e.g., located at an intersectionbetween two antenna zones, three antenna zones, or four antenna zones).In performing the adjacent zone search 1007, the near-field charging padidentifies (1142) adjacent antenna zones (ZAs) to the selected antennazone Z1. In some embodiments, identifying adjacent zones (ZAs) includesidentifying up to five adjacent zones.

Next, the near-field charging pad pairs (1144) the selected antenna zoneZ1 with each identified adjacent zone and sweeps (1146) across allantenna tuning combinations and sweeps (1148) across all availablefrequencies (and perhaps other transmission characteristics).Thereafter, the near-field charging pad selects (1150) a combination ofantenna zones from among the adjacent zones (ZAs). For example, thenear-field charging pad may determine that the selected antenna zone Z1deliver a higher amount of power to the wireless power receiver thaneither of these antenna zones is individually able to deliver to thewireless power receiver. In another example, the near-field charging padmay determine that the selected antenna zone Z1 and two (or three) otheradjacent zones deliver a maximum amount of power to the wireless powerreceiver. When selecting the desired combination of antenna zones, thenear-field charging pad records the transmission characteristics used toproduce the maximum amount of power delivered to the wireless powerreceiver. Performing the fine search and the adjacent zone search arealso discussed in more detail above with reference to steps 924-932 ofthe method 900.

After performing the fine search 1006 (and the adjacent zone search 1007if needed), the near-field charging pad executes (1008) a power controlroutine, an example of which is illustrated in FIG. 11E. In someembodiments, the power control routine allows both the wireless powerreceiver and the near-field charging pad to continually monitor anamount of power being delivered to the wireless power receiver. In thisway, adjustments to the wireless power transmission can be made based onfeedback received from the wireless power receiver. For example, if thedelivered power is below a configured threshold, then the wireless powerreceiver may request a power increase from the near-field charging pad.FIG. 11E illustrates various operations that may be used to allow thereceiver to request an increase or a decrease in an amount of wirelesspower delivered to the receiver, and also illustrates a process executedby the near-field charging pad to determine when to increase or decreasethe amount of wireless power delivered to the receiver in response tothe receiver's requests for increases or decreases in the amount ofwireless power delivered.

The antenna elements 120 described above (e.g., in reference to FIG. 1B)may also be configured to have multiple adaptive load terminals (e.g.,multiple adaptive load terminals 121) that are coupled to at differentpositions along a respective antenna element 120. An example of anantenna element 120 with multiple adaptive load terminals is providedbelow in reference to FIG. 12. FIG. 12 is a schematic showing atransmitting antenna element (unit cell) with a plurality of adaptiveloads (which may be a part of an array of such antennas, as describedabove in reference to FIGS. 3-8) of an RF charging pad, in accordancewith some embodiments. In some embodiments, the RF charging pad 1200includes one or more antenna elements 1201 (which may be any of theantenna elements as shown in FIGS. 3B, 4, 6A-6E, 7A-7D, and 8). Eachantenna element 1201 is powered/fed by a respective power amplifier (PA)switch circuit 1208 (which may be a respective one of the PA switchcircuits 103 of FIG. 3A) that may be connected to a respective poweramplifier 1208 or a source of power at a first end of the antennaelement 1201.

In some embodiments, the input circuit that includes the power amplifier1208 may additionally include a device that can change frequencies ofthe input signal or a device that can operate at multiple frequencies atthe same time, such as an oscillator or a frequency modulator.

In some embodiments, each antenna element 1201 of the RF charging pad1200 includes a plurality of respective adaptive load terminals 1202,for example, 1202 a, 1202 b, 1202 c, . . . 1202 n, at a plurality ofpositions within a respective antenna element 1201. In some embodiments,the antenna element 1201 includes a conductive line forming a meanderedline pattern (as discussed above in reference to FIGS. 3, 4, and 6-8).In some embodiments, each adaptive load terminals of the plurality ofadaptive load terminals 1202 for the antenna element 1201 is located atdifferent positions on the conductive meandered line of the antennaelement 1201 as shown in FIG. 12.

In some embodiments, a meandered line antenna element 1201 includes aconductive line with multiple turns in one plane. In some embodiments,the multiple turns may be square turns as shown for the antenna element1201 in FIG. 12. In some embodiments, the multiple turns may beround-edged turns. The conductive line may also have segments of varyingwidths, for example, a segment 1206 having a first width, andshort-length segment 1207 that has a second width that is less than thefirst width. In some embodiments, at least one of the adaptive loadterminals 1202 a is positioned at one of the short-length segments(e.g., short-length segment 1207) and another adaptive load terminal ispositioned anywhere at one of the segments 1206 having the first width.In some embodiments, at least one of the adaptive load terminals 1202 ispositioned or connected anywhere on a width segment, for example, at themiddle of a width segment of the meandered line antenna element 1201. Insome embodiments, the last adaptive load terminal 1202 n is positionedat a second end of the conductive line (opposite to a first end at theinput terminal 1203 of the antenna element 1201 described above inreference to FIGS. 3, 4, and 6-8). In some embodiments, in certaindesign and optimization, an adaptive load terminal is not necessarilypositioned at a second end of the meandered line antenna element 1201but can be positioned at any location of the antenna element 1201.

In some embodiments, the RF charging pad 1200 also includes (or is incommunication with) a central processing unit 1210 (also referred tohere as processor 1210). In some embodiments, the processor 1210 isconfigured to control RF signal frequencies and to control impedancevalues at each of the adaptive load terminals 1202, e.g., bycommunicating with a plurality of the load picks or adaptive loads 1212,for example, 1212 a, 1212 b, 1212 c, . . . 1212 n, for each of theadaptive load terminals 1202 (as discussed above in reference to loadpick or adaptive load 106 in FIGS. 3A and 3B).

In some embodiments, an electronic device (e.g., a device that includesa receiver 1204 as an internally or externally connected component, suchas a remote that is placed on top of a charging pad 1200 that may beintegrated within a housing of a streaming media device or a projector)and uses energy transferred from one or more RF antenna elements 1201 ofthe charging pad 1200 to the receiver 1204 to charge a battery and/or todirectly power the electronic device.

In some embodiments, the adaptive load terminals 1202 at a particularzone or selected positions of the antenna element 1201 (e.g., a zone onthe antenna element 1201 located underneath a position at which anelectronic device (with an internally or externally connected RFreceiver 1204) to be charged is placed on the charging pad) areoptimized in order to maximize power received by the receiver 1204. Forexample, the CPU 1210 upon receiving an indication that an electronicdevice with an internally or externally connected RF receiver 1204 hasbeen placed on the pad 1200 in a particular zone on the antenna element1201 may adapt the plurality of adaptive loads 1212, for example,adaptive loads 1212 a, 1212 b, 1212 c, . . . 1212 n, that arerespectively coupled to the adaptive terminals 1202, in order tomaximize power transferred to the RF receiver 1204. Adapting the set ofadaptive loads 1212 may include the CPU 1210 commanding one or more ofthe adaptive loads to try various impedance values for one or more ofthe adaptive load terminals 1202 that are coupled to different positionsof the antenna element 1201. Additional details regarding adaptingadaptive loads were provided above, and, for the sake of brevity, arenot repeated here.

The effective impedance value (Z_(effective)) at a particularposition/portion of the conductive line of the antenna element 1201 isaffected by a number of variables and may be manipulated by adjustingconfigurations of the adaptive load terminals 1212 that are coupled tovarious positions on the antenna element 1201. In some embodiments, aneffective impedance value (Z_(effective)), starting from a point thatdivides sections 1225 (which starts at the terminal 1203 of the antennaelement 1201 and extends to an edge of the receiver 1204) and 1227(which is formed by the rest of the transmitting antenna element 1201and the terminal 1202 n) and ending at the TX antenna 1201's connectionto the adaptive load 1212 n (e.g., terminal 1202 n) will change based onlocation of the receiver 1204 on the TX antenna 1201 and based on a setof selected loads provided by adaptive loads 1212 at various positionswithin section 1227. In some embodiments, the selected loads areoptimized by the adaptive loads 1212 (in conjunction with the processor1210) to tune Z_(effective) in such a way that the energy transferredbetween terminal 1203 and the receiver 1204 reaches a maximum (e.g., 75%or more of energy transmitted by antenna elements of the pad 1200 isreceived by the RF receiver 1204, such as 98%), while energy transfermay also stay at a minimum from terminal 1203 to terminal 1202 n (e.g.,less than 25% of energy transmitted by antenna elements of the pad 1200is not received by the RF receiver 1204 and ends up reaching terminalspositioned within section 1227 or ends up being reflected back,including as little as 2%).

In some embodiments, a selected several adaptive loads 1212 of theplurality of adaptive loads 1212 are used (by the processor 1210) on theantenna element 1201 to adjust the impedance and/or frequency of theantenna element 1201. In one example, with reference to FIG. 12, onlyadaptive load terminals 1202 a and 1202 c are connected at a particularpoint in time to adaptive loads 1212 a and 1212 c respectively, whileadaptive load terminals 1202 b and 1202 n are disconnected at theparticular point in time. In another example, with reference to FIG. 12,only adaptive load terminals 1202 a and 1202 n are connected at aparticular point in time to adaptive loads 1212 a and 1212 n,respectively, while adaptive load terminals 1202 b and 1202 c aredisconnected at the particular point in time. In some embodiments, allof the adaptive load terminals 1202 are connected at a particular pointin time to their respective adaptive loads 1212. In some embodiments,none of the adaptive load terminals 1202 are connected at a particularpoint in time to their respective adaptive loads 1212. In someembodiments, the impedance value of each of the adaptive loads 1212connected to a selected adaptive load terminal 1212 is adjustedindividually to optimize the energy transfer.

In embodiments in which a meandered line antenna has been optimized forthe multi-band operation, the multiple adaptive load configurationwithin a single antenna element also enables a broader frequency bandadjustment compared with a single adaptive load configuration within asingle antenna element as described in FIG. 3B above. The multipleadaptive load configuration within a single antenna element furtherenhances multiple frequency band operation on a single antenna element.For example, a single antenna element 1201 with multiple adaptive loadterminals is capable of operating at a wider frequency band than acorresponding antenna element that is configured with one adaptive loadterminal.

In some embodiments, adapting the set of adaptive loads 1212 also oralternatively includes the CPU 1210 causing the set of antenna elementsto transmit RF signals at various frequencies until a frequency is foundat which a maximum amount of energy is transferred to the RF receiver1204. In some embodiments, for example, one of the antenna elementstransmits RF signals at a first frequency, and another one of theantenna elements transmits RF signals at a second frequency that isdifferent from the first frequency. In some embodiments, adjusting theimpedance value and/or the frequencies at which the set of antennaelements transmits causes changes to the amount of energy transferred tothe RF receiver 1204. In this way, the amount of energy transferred tothe RF receiver 1204 that is maximized (e.g., to transfer at least 75%of the energy transmitted by antenna elements of the pad 1200 to thereceiver 1204, and in some embodiments, adjusting the impedance valueand/frequencies may allow up to 98% of the energy transmitted to bereceived by the receiver 1204) may be received at any particular pointon the pad 1200 at which the RF receiver 1204 might be placed.

In some embodiments, the CPU 1210 determines that a maximum amount ofenergy is being transferred to the RF receiver 1204 when the amount ofenergy transferred to the RF receiver 1204 crosses a predeterminedthreshold (e.g., 75% or more of transmitted energy is received, such asup to 98%) or by testing transmissions with a number of impedance and/orfrequency values and then selecting the combination of impedance andfrequency that results in maximum energy being transferred to the RFreceiver 1204 (also as described in reference to the adaptation schemein FIGS. 3A-3D above). In some embodiments, processor 1210 is connectedto the receiver 1204 through a feedback loop (e.g. by exchangingmessages using a wireless communication protocol, such as BLUETOOTH lowenergy (BLE), WIFI, ZIGBEE, infrared beam, near-field transmission, etc,to exchange messages). In some embodiments, the adaptation scheme isemployed to test various combinations of impedance values of theadaptive impedance loads 1212 and RF frequencies, in order to maximizeenergy transferred to an RF receiver 1204. In such embodiments, each ofthe adaptive load 1212 is configured to adjust the impedance value alonga range of values, such as between 0 and infinity. In some embodiments,the adaptation scheme is employed when one or more RF receivers areplaced on top of one of the antenna element 1201.

In some embodiments, an adaptation scheme is employed to adaptivelyadjust the impedance values and/or frequencies of the RF signal(s)emitted from the RF antenna(s) 1201 of the charging pad 1200, in orderto determine which combinations of frequency and impedance result inmaximum energy transfer to the RF receiver 1204. For example, theprocessor 1210 that is connected to the charging pad 1200 triesdifferent frequencies (i.e., in the allowed operating frequency range orranges) by using different selected sets of adaptive loads 1212 atdifferent locations of the antenna element 1201, e.g. enabling ordisabling certain adaptive loads 1212, to attempt to adaptively optimizefor better performance. For example, a simple optimization eitheropens/disconnects or closes/shorts each load terminal to ground (inembodiments in which a relay is used to switch between these states),and may also cause RF antenna element 1201 to transmit at variousfrequencies. In some embodiments, for each combination of relay state(open or shorted) and frequency, the energy transferred to the receiver1204 is monitored and compared to energy transferred when using othercombinations. The combination that results in maximum energy transfer tothe receiver 1204 is selected and used to continue to transmitting theone or more RF signals using one or more antenna elements 1201 to thereceiver 1204.

In some embodiments, the single antenna element 1201 with multipleadaptive loads 1212 of the pad 1200 may be configured to operate in twoor more distinct frequency bands (such as the ISM bands describedabove), e.g., a first frequency band with a center frequency of 915 MHzand a second frequency band with a center frequency of 5.8 GHz. In theseembodiments, employing the adaptation scheme may include transmitting RFsignals and then adjusting the frequency at first predeterminedincrements until a first threshold value is reached for the firstfrequency band and then adjusting the frequency at second predeterminedincrements (which may or may not be the same as the first predeterminedincrements) until a second threshold value is reached for the secondfrequency band. In some embodiments, a single antenna element canoperate at multiple different frequencies within one or more frequencybands. For example, the single antenna element 1201 may be configured totransmit at 902 MHz, 915 MHz, 928 MHZ (in the first frequency band) andthen at 5.795 GHz, 5.8 GHz, and 5.805 GHz (in the second frequencyband). The single antenna element 1201 can operate at more than onefrequency bands as a multi-band antenna. A transmitter with at least oneantenna element 1201 can be used as a multi-band transmitter.

In some embodiments, multiple antenna elements 1201 each with multipleadaptive loads 1212 may be configured within a particular transmissionpad to allow the particular transmission pad to operate in two or moredistinct frequency bands respectively at the same time. For example, afirst antenna element 1201 of the particular transmission pad operatesat a first frequency or frequency band, a second antenna element 1201 ofthe particular transmission pad operates at a second frequency orfrequency band, and a third antenna element 1201 of the particulartransmission pad operates at a third frequency or frequency band, and afourth antenna element 1201 of the particular transmission pad operatesat a fourth frequency or frequency band, and the four frequency bandsare distinct from each other. In this way, the particular transmissionpad is configured to operate at multiple different frequency bands.

In some embodiments, the transmitter described herein can transmitwireless power in one frequency or frequency band, and transmit andexchange data with a receiver in another frequency or frequency band.

Different antenna elements operating at different frequencies canmaximize energy transfer efficiency when a smaller device is chargedwith higher frequencies and a larger device is charged with lowerfrequencies on the same charging pad. For example, devices that requirea higher amount of power, such as mobile phones, may also have morespace to include larger antennas, thus making a lower frequency of 900MHz a suitable frequency band. As a comparison, a smaller device, suchas an earbud, may require a small amount of power and may also have lessspace available for longer antennas, thus making a higher frequency of2.4 or 5.8 GHz a suitable frequency band. This configuration enablesmore flexibility in the types and sizes of antennas that are included inreceiving devices.

Turning now to FIG. 13, in accordance with some embodiments, a flowchart of a method 1300 of charging an electronic device through radiofrequency (RF) power transmission by using at least one RF antenna witha plurality of adaptive loads is provided. Initially, a charging padincluding a transmitter is provided in step 1302 that includes at leastone RF antenna (e.g., antenna element 1201, as described with respect toFIG. 12 above which further includes FIGS. 3-8) for transmitting one ormore RF signals or waves, i.e., an antenna designed to and capable oftransmitting RF electromagnetic waves. In some embodiments, an array ofRF antenna elements 1201 are arranged adjacent to one another in asingle plane, in a stack, or in a combination of thereof, thus formingan RF charging pad 1200 (as described in reference to FIGS. 6A-6E, 7A-7Dand 8). In some embodiments, the RF antenna elements 1201 each includean antenna input terminal (e.g., the first terminal 1203 discussed abovein reference to FIG. 12) and a plurality of antenna output terminals(e.g., the plurality of adaptive load terminals 1202 discussed above inreference to FIG. 12). In some embodiments, the antenna element 1201includes a conductive line that forms a meandered line arrangement (asshown in FIGS. 3-4, and 6-12). The plurality of adaptive load terminals1202 are positioned at different locations of the conductive line of theantenna element 1201.

In some embodiments, the transmitter further comprises a power amplifierelectrically coupled between the power input and the antenna inputterminal (e.g., PA 1208 in FIG. 12). Some embodiments also includerespective adaptive loads 1212 a, 1212 b, 1212 c, . . . 1212 nelectrically coupled to the plurality of antenna output terminals (e.g.,adaptive load terminals 1202 in FIG. 12). In some embodiments, thetransmitter includes a power input configured to be electrically coupledto a power source, and at least one processor (e.g., processor 1210 inFIG. 12, and processor 110 in FIGS. 3A-3B) configured to control atleast one electrical signal sent to the antenna. In some embodiments,the at least one processor is also configured to control the frequencyand/or amplitude of the at least one signal sent to the antenna.

In some embodiments, each RF antenna of the transmitter includes: aconductive line forming a meandered line pattern, a first terminal(e.g., terminal 1203) at a first end of the conductive line forreceiving current that flows through the conductive line at a frequencycontrolled by one or more processors, and a plurality of adaptive loadterminals (e.g., terminals 1202), distinct from the first terminal, at aplurality of positions of the conductive line, the plurality of adaptiveload terminals coupled to a respective component (e.g., adaptive loads1212 in FIG. 12) controlled by the one or more processors and thatallows for modifying an impedance value of the conductive line. In someembodiments, the conductive line is disposed on or within a firstantenna layer of a multi-layered substrate. Also in some embodiments, asecond antenna is disposed on or within a second antenna layer of themulti-layered substrate. Finally, some embodiments also provide a groundplane disposed on or within a ground plane layer of the multi-layeredsubstrate.

In some embodiments, a receiver (e.g., receiver 1204 in reference toFIG. 12) is also provided (also as described in reference to FIG. 3).The receiver also includes one or more RF antennas for receiving RFsignals. In some embodiments, the receiver includes at least onerectenna that converts the one or more RF signals into usable power tocharge a device that includes the receiver 1204 as an internally orexternally connected component (see also steps 504, 506, 510, 514 and518 in reference to FIG. 5). In use, the receiver 1204 is placed withina near-field radio frequency distance to the at least one antenna of thetransmitter or the charging pad. For example, the receiver may be placedon top of the at least one RF antenna 1201 or on top of a surface thatis adjacent to the at least one RF antenna 1201, such as a surface of acharging pad 1200.

In step 1304, one or more RF signals are then transmitted via at theleast one RF antenna 1201.

The system is then monitored in step 1306 to determine the amount ofenergy that is transferred via the one or more RF signals from the atleast one antenna 1201 to one or more RF receivers (as is also discussedabove). In some embodiments, this monitoring 1306 occurs at thetransmitter, while in other embodiments the monitoring 1306 occurs atthe receiver which sends data back to the transmitter via a back channel(e.g., over a wireless data connection using WIFI or BLUETOOTH). In someembodiments, the transmitter and the receiver exchange messages via theback channel, and these messages may indicate energy transmitted and/orreceived, in order to inform the adjustments made at step 1308.

In some embodiments, in step 1308, a characteristic of the transmitteris adaptively adjusted to attempt to optimize the amount of energy thatis transferred from the at least one RF antenna 1201 to the receiver. Insome embodiments, this characteristic is a frequency of the one or moreRF signals and/or an impedance of the transmitter. In some embodiments,the impedance of the transmitter is the impedance of the adjustableloads. Also in some embodiments, the at least one processor is alsoconfigured to control the impedance of the selected set of the pluralityof adaptive loads 1212. Additional details and examples regardingimpedance and frequency adjustments are provided above.

In some embodiments, the at least one processor (e.g. CPU 1210 in FIG.12) dynamically adjusts the impedance of the adaptive load based on themonitored amount of energy that is transferred from the at least oneantenna 1201 to the RF receiver. In some embodiments, the at least oneprocessor simultaneously controls the frequency of the at least onesignal sent to the antenna.

In some embodiments, the single antenna element 1201 with multipleadaptive loads 1212 of the pad 1200 may be dynamically adjusted by theone or more processors to operate in two or more distinct frequencybands (such as the ISM bands described above) at the same time or atdifferent times, e.g., a first frequency band with a center frequency of915 MHz and a second frequency band with a center frequency of 5.8 GHz.In these embodiments, employing the adaptation scheme may includetransmitting RF signals and then adjusting the frequency at firstpredetermined increments until a first threshold value is reached forthe first frequency band and then adjusting the frequency at secondpredetermined increments (which may or may not be the same as the firstpredetermined increments) until a second threshold value is reached forthe second frequency band. For example, the single antenna element 1201may be configured to transmit at 902 MHz, 915 MHz, 928 MHZ (in the firstfrequency band) and then at 5.795 GHz, 5.8 GHz, and 5.805 GHz (in thesecond frequency band). The single antenna element 1201 can operate atmore than one frequency bands as a multi-band antenna. A transmitterwith at least one antenna element 1201 can be used as a multi-bandtransmitter.

In some embodiments, a charging pad or transmitter may include one ormore of the antenna element 1201 with a plurality of adaptive loads asdescribed in FIG. 12 and one or more antenna element 120 with oneadaptive load as described in FIG. 3A-3D.

FIGS. 14A-14D are schematics showing various configurations forindividual antenna elements that can operate at multiple frequencies orfrequency bands within an RF charging pad, in accordance with someembodiments. As shown in FIGS. 14A-14D, an RF charging pad 100 (FIGS.3A-3B) or an RF charging pad 1200 (FIG. 12) may include antenna elements120 (FIG. 3B) or 1201 (FIG. 12) that configured to have conductive lineelements that have varying physical dimensions.

For example, FIGS. 14A-14D show examples of structures for an antennaelement that each include a conductive line formed into differentmeandered line patterns at different portions of the element. Theconductive lines at different portions or positions of the element mayhave different geometric dimensions (such as widths, or lengths, ortrace gauges, or patterns, spaces between each trace, etc.) relative toother conductive lines within an antenna element. In some embodiments,the meandered line patterns may be designed with variable lengths and/orwidths at different locations of the pad (or an individual antennaelement). These configurations of meandered line patterns allow for moredegrees of freedom and, therefore, more complex antenna structures maybe built that allow for wider operating bandwidths and/or couplingranges of individual antenna elements and the RF charging pad.

In some embodiments, the antennas elements 120 and 1201 described hereinmay have any of the shapes illustrated in FIGS. 14A-14D. In someembodiments, each of the antenna elements shown in FIGS. 14A-14D has aninput terminal (123 in FIG. 1B or 1203 in FIG. 12) at one end of theconductive line and at least one adaptive load terminals (121 in FIG. 1Bor 1202 a-n in FIG. 12) with adaptive loads (106 in FIG. 1B or 1212 a-nin FIG. 12) as described above at another end or a plurality ofpositions of the conductive line.

In some embodiments, each of the antenna elements shown in FIGS. 14A-14Dcan operate at two or more different frequencies or two or moredifferent frequency bands. For example, a single antenna element canoperate at a first frequency band with a center frequency of 915 MHz ata first point in time and a second frequency band with a centerfrequency of 5.8 GHz at a second point in time, depending on whichfrequency is provided at an input terminal of each of the antennaelements. Moreover, the shapes of the meandered line patterns shown inFIGS. 14A-14D are optimized to allow the antenna elements to operateefficiently at multiple different frequencies.

In some embodiments, each of the antenna elements shown in FIGS. 14A-14Dcan operate at two or more different frequencies or two or moredifferent frequency bands at the same time when the input terminal issupplied with more than two distinct frequencies that can besuperimposed. For example, a single antenna element can operate at afirst frequency band with a center frequency of 915 MHz and a secondfrequency band with a center frequency of 5.8 GHz at the same time whenboth frequency bands with a first center frequency of 915 MHz and asecond center frequency of 5.8 GHz are supplied at the input terminal ofthe conductive line. In yet another example, a single antenna elementcan operate at multiple different frequencies within one or morefrequency bands.

In some embodiments, the operating frequencies of the antenna elementscan be adaptively adjusted by one or more processors (110 in FIGS. 3A-3Bor 1210 in FIG. 12) as described above according to the receiver antennadimension, frequency, or the receiver loads and the adaptive loads onthe charging pad.

In some embodiments, each of the antenna elements shown in FIGS. 14A-14Dwith different meandered patterns at different portions of theconductive line can operate more efficiently at multiple frequenciescompared with the more symmetrical meandered line structures (Forexample, FIG. 3B, 4, 6A-6B, or 8). For example, energy transferefficiency at different operating frequencies of the antenna elementsshown in FIGS. 14A-14D with different meandered patterns at differentportions of the conductive line can be improved by about at least 5%,and in some instance at least 60%, more than the more symmetricalmeandered line structure elements. For example, the more symmetricalmeandered line structure antenna element may be able to transfer no morethan 60% of transmitted energy to a receiving device while operating ata new frequency other than a frequency for which the more symmetricalmeandered line structure antenna element has been designed (e.g., if themore symmetrical meandered line structure antenna element is designed tooperate at 900 MHz, if it then transmits a signal having a frequency of5.8 GHz it may only be able to achieve an energy transfer efficiency of60%). In contrast, the antenna element with different meandered patterns(e.g., those shown in FIGS. 14A-14D) may be able to achieve an energytransfer efficiency of 80% or more while operating at variousfrequencies. In this way, the designs for antenna elements shown inFIGS. 14A-14D ensure that a single antenna element is able to achieve amore efficient operation at various different frequencies.

FIG. 15 is schematic showing an example configuration for an individualantenna element that can operate at multiple frequencies or frequencybands by adjusting the length of the antenna element, in accordance withsome embodiments.

In some embodiments as shown in FIG. 15, at least one transmittingantenna element 1502 (as described in FIGS. 3-8 and 13-14) of the one ormore transmitting antenna elements of an RF charging pad 1500 has afirst conductive segment 1504 (a first portion of a meandered conductiveline, such as any of those described above for antenna elements 120 and1201) and a second conductive segment 1506 (a second portion of themeandered conductive line, such as any of those described above forantenna elements 120 and 1201). In some embodiments, the firstconductive segment includes an input terminal (123 in FIG. 3B or 1203 inFIG. 12). In some embodiments, the at least one transmitting antennaelement 1502 is configured to operate at a first frequency (e.g., 2.4GHz) while the first conductive segment 1504 is not coupled with thesecond conductive segment 1506. In some embodiments, the at least onetransmitting antenna element 1502 is configured to operate at a secondfrequency (e.g., 900 MHz) which is different from the first frequencywhile the first conductive segment is coupled with the second conductivesegment.

In some embodiments, one or more processors (110 in FIGS. 3A-3B or 1210in FIG. 12) are configured to cause coupling of the first segment withthe second segment in conjunction with instructing a feeding element (asdescribed as 108 in FIGS. 3A-3B and 1208 in FIG. 12) to generate currentwith a second frequency (e.g., 900 MHz) that is distinct from the firstfrequency (e.g., 2.4 GHz), thereby allowing the antenna element 1502 tomore efficiently operate at the second frequency. The one or moreprocessor may also be configured to cause de-coupling of the secondconductive segment from the first conductive segment in conjunction withinstructing the feeding element to generate current with the firstfrequency instead of the second frequency, thereby allowing the antennaelement 1502 to more efficiently operate at the first frequency again.In some embodiments, the one or more processors are configured todetermine whether to causing the coupling (or de-coupling) of theseconductive segments based on information received from a receiver (e.g.,RX 104 or 1204) that identifies a frequency at which the receiver isconfigured to operate (e.g., for larger devices with longer receivingantennas, this frequency may be 900 MHz, while for smaller devices withsmall receiving antennas, this frequency may be 2.4 GHz).

In some embodiments, the coupling described here in FIG. 15 can beimplemented by directly connecting two different segments of a singleantenna element 1502 while bypassing the conductive line locatedin-between the two connection points or the two different segments. Insome embodiments, coupling can be implemented between more than twodifferent segments of the antenna element 1502. The coupling of thedifferent portions or segments of a single meandered line antennaelement 1502 can effectively change the size or length of the conductiveline of the antenna element 1502, and therefore enable the singleantenna element 1502 to operate at different frequencies. The singleantenna element 1502 may also operate at more than one frequency bandsas a multi-band antenna.

FIG. 16A shows a top perspective view of a schematic drawing of anexemplary near-field power transfer system 1600. FIG. 16B shows a bottomperspective view of a schematic drawing of an exemplary near-field powertransfer system 1600. The power transfer system 1600 may comprise a topsurface 1601, a bottom surface 1602, and sidewalls 1603. In someembodiments, a housing containing components of the power transfersystem 1600 may be constructed of a material creating minimalobstructions for electromagnetic waves to pass through. In otherembodiments, different portions of the housing may be constructed withmaterials having different electromagnetic properties such aspermeability and permittivity. For example, the top surface 1601 mayallow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 1603 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

The power transfer system 1600 may radiate RF energy and thus transferpower when the power transfer system 1600 is adjacent to a second powertransfer system (not shown). As such, a power transfer system 1600 maybe on a “transmit side,” so as to function as a power transmitter, orthe power transfer system 1600 may be on a “receive side,” so as tofunction as a power receiver. In some embodiments, where the powertransfer system 1600 is associated with a transmitter, the powertransfer system 1600 (or subcomponents of the power transfer system1600) may be integrated into the transmitter device, or may beexternally wired to the transmitter. Likewise, in some embodiments,where the power transfer system 1600 is associated with a receiver, thepower transfer system 1600 (or subcomponents of the power transfersystem 1600) may be integrated into the receiver device, or may beexternally wired to the receiver.

A substrate 1607 may be disposed within a space defined between the topsurface 1601, sidewalls 1603, and the bottom surface 1602. In someembodiments, the power transfer system 1600 may not include a housingand the substrate 1607 may include the top surface 1601, sidewalls 1603,and the bottom surface 1602. The substrate 1607 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may generate radiation, andmay act as thin reflectors.

An antenna 1604 may be constructed on or below the top surface 1601.When the power transfer system 1600 is associated with a powertransmitter, the antenna 1604 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system1600 is associated with a power receiver, the antenna 1604 may be usedfor receiving electromagnetic waves. In some embodiments, the powertransfer system 1600 may operate as a transceiver and the antenna 1604may both transmit and receive electromagnetic waves. The antenna 1604may be constructed from materials such as metals, alloys, metamaterialsand composites. For example, the antenna 1604 may be made of copper orcopper alloys. The antenna 1604 may be constructed to have differentshapes based on the power transfer requirements. In the exemplary system1600 shown in FIG. 16A and FIG. 16B, the antenna 1604 is constructed ina shape of a spiral including antenna segments 1610 that are disposedclose to each other. The currents flowing through the antenna segments1610 may be in opposite directions. For example, if the current in theantenna segment 1610 b is flowing from left to right of FIG. 16A, thecurrent each of the antenna segments 1610 a, 1610 c may be flowing fromright to left. The opposite flow of the current results in mutualcancellation of the electromagnetic radiation the far field of the powertransfer system 1600. In other words, the far field electromagneticradiation generated by one or more antenna segments 1610 left of animaginary line 1615 is cancelled out by the far field electromagneticradiation generated by one or more antenna segments 1610 right of theline 1615. Therefore, there may be no leakage of power in the far fieldof the power transfer system 1600. Such cancellation, however, may notoccur in a near-field active zone of the power transfer system 1600,where the transfer of power may occur.

The power transfer system 1600 may include a ground plane 1606 at orabove the bottom surface 1602. The ground plane 1606 may be formed bymaterials such as metal, alloys, and composites. In an embodiment, theground plane 1606 may be formed by copper or a copper alloy. In someembodiments, the ground plane 1606 may be constructed of a solid sheetof material. In other embodiments, the ground plane 1606 may beconstructed using material strips arranged in shapes such as loops,spirals, and meshes. A via 1605 carrying a power feed line (not shown)to the antenna may pass through the ground plane 1606. The power feedline may supply current to the antenna 1604. In some embodiments, theground plane 1606 may be electrically connected to the antenna 1604. Insome embodiments, the ground plane 1606 may not be electricallyconnected to the antenna 1604. For such implementations, an insulationarea 1608 to insulate the via 1605 from the ground plane 1606 may beconstructed between the via 1605 and the ground plane 1606. In someembodiments, the ground plane 1606 may act as a reflector of theelectromagnetic waves generated by the antenna 1604. In other words, theground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 1600 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 1604 from ortowards the top surface 1601. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface 1602.

Therefore, as a result of the antenna 1604 and the ground plane 1606,the electromagnetic waves transmitted or received by the power transfersystem 1600 accumulate in the near field of the system 1600. The leakageto the far field of the system 1600 is minimized.

FIG. 17A schematically illustrates a top perspective view of anexemplary near-field power transfer system 1700, according to anembodiment of the disclosure. In some embodiments, the power transfersystem 1700 may be a part of or associated with a power transmitter. Inother embodiments, the power transfer system 1700 may be a part of orassociated with a power receiver. The power transfer system 1700 maycomprise a housing defined by a top surface 1701, a bottom surface (notshown), and sidewalls 1703. In some embodiments, the housing may beconstructed of a material creating minimal obstructions forelectromagnetic waves to pass through. In other embodiments, differentportions of the housing may be constructed with materials havingdifferent electromagnetic properties such as permeability andpermittivity. For example, the top surface 1701 may allowelectromagnetic waves to pass through with minimal obstruction while thesidewalls 1703 may obstruct electromagnetic waves by attenuation,absorption, reflection, or other techniques known in the art.

A substrate 1707 may be disposed within a space defined between the topsurface 1701, sidewalls 1703, and the bottom surface 1702. In someembodiments, the power transfer system 1700 may not include a housingand the substrate 1707 may include the top surface 1701, sidewalls 1703,and the bottom surface 1702. The substrate 1707 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may generate radiation, andmay act as thin reflectors.

An antenna 1704 may be constructed on or below the top surface 1701.When the power transfer system 1700 is a part of or associated with apower transmitter, the antenna 1704 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system1700 is a part of or associated with a power receiver, the antenna 1704may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 1700 may operate as a transceiver and theantenna 1704 may both transmit and receive electromagnetic waves. Theantenna 1704 may be constructed from materials such as metals, alloys,metamaterials, and composites. For example, the antenna 1704 may be madeof copper or copper alloys. The antenna 1704 may be constructed to havedifferent shapes based on the power transfer requirements. In theexemplary system 1700 shown in FIG. 17A the antenna 1704 is constructedin a shape of a spiral including antenna segments which are disposedclose to each other. A signal feed line (not shown) may be connected tothe antenna 1704 through a via 1705.

FIG. 17B schematically illustrates a side view of the exemplary powertransmission system 1700. As shown, an upper metal layer may form theantenna 1704, and a lower metal layer may form the ground plane 1706.The substrate 1707 may be disposed in between the upper and lower metallayer. The substrate 1707 may include materials such as FR4,metamaterials, or any other materials known in the art. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may have to be based upon power-transfer requirements,and/or compliance constraints for government regulations. Themetamaterials disclosed herein may receive radiation or generateradiation, and may act as thin reflectors.

FIG. 17C schematically illustrates a top perspective view of antenna1704. The antenna 1704 comprises a connection point 1709 for a feed line(not shown) coming through the via 1705. FIG. 17D schematicallyillustrates a side perspective view of the ground plane 1706. In anembodiment, the ground plane 1706 comprises a solid metal layer. Inother embodiments, the ground plane 1706 may include structures such asstripes, meshes, and lattices and may not be completely solid. Theground plane 1706 may also comprise a socket 1709 for the via 1705 topass through. Around the socket 1709, the ground plane 1706 may alsoinclude an insulating region 1710 to insulate the socket 1709 from therest of the ground plane 1706. In some embodiments, the ground plane mayhave an electrical connection to a line coming through the via, and theinsulating region 1710 may not be required.

FIG. 18 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 1800, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 1800 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 1800 may be a part of or associated with apower receiver. The power transfer system 1800 may comprise a housingdefined by a top surface 1801, a bottom surface (not shown), andsidewalls 1803. In some embodiments, the housing may be constructed of amaterial creating minimal obstructions for electromagnetic waves to passthrough. In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 1801may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 1803 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 1807 may be disposed within a space defined between the topsurface 1801, sidewalls 1803, and the bottom surface 1802. In someembodiments, the power transfer system 1800 may not include a housingand the substrate 1807 may include the top surface 1801, sidewalls 1803,and the bottom surface 1802. The substrate 1807 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thinreflectors.

An antenna 1804 may be constructed on or below the top surface. When thepower transfer system 1800 is a part of or associated with a powertransmitter, the antenna 1804 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system1800 is a part of or associated with a power receiver, the antenna 1804may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 1800 may operate as a transceiver and theantenna 1804 may both transmit and receive electromagnetic waves. Theantenna 1804 may be constructed from materials such as metals, alloys,metamaterials and composites. For example, the antenna 1804 may be madeof copper or copper alloys. The antenna 1804 may be constructed to havedifferent shapes based on the power transfer requirements. In theexemplary system 1800 shown in FIG. 18, the antenna 1804 is constructedin a shape of a dipole including a first meandered pole 1809 a and asecond meandered pole 1809 b. A first power feed line (not shown) to thefirst meandered pole 1809 a may be carried by a first via 1805 a and asecond power feed line (not shown) to the second meandered pole 1809 bmay be carried by a second via 1805 b. The first power feed line maysupply current to the first meandered pole 1809 a and the second powerfeed line may supply current to the second meandered pole 1809 b. Thefirst meandered pole 1809 a includes antenna segments 1810 which aredisposed close to each other and the second meandered pole 1809 bincludes antenna segments 1811 also disposed close to each other. Thecurrents flowing through the neighboring antenna segments 1810, 1811 maybe in opposite directions. For example, if the current in an antennasegment 1810 b is flowing from left to right of FIG. 18, the current ineach of the antenna segments 1810 a, 1810 c may be flowing from right toleft. The opposite flow of the current across any number of antennasegments 1810 of the power transfer system 1800 results in mutualcancellation of the far field electromagnetic radiation generated by thepower transfer system 1800. Additionally or alternatively, the far fieldelectromagnetic radiation generated by the antenna segments 1810 of thefirst pole 1809 a may be cancelled by the electromagnetic radiationgenerated by antenna segments 1811 of the second pole 1809 b. It shouldbe appreciated that the far field cancellation may occur across anynumber of segments 1810, 1811 and/or across any number of poles 1809.Therefore, there may be no leakage of power in the far field of thepower transfer system 1800. Such cancellation, however, may not occur ina near-field active zone of the power transfer system 1800, where thetransfer of power may occur.

The power transfer system 1800 may include a ground plane (not shown) ator above the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, and composites. In an embodiment, the groundplane may be formed by copper or a copper alloy. In some embodiments,the ground plane may be constructed of a solid sheet of material. Inother embodiments, the ground plane may be constructed using materialstrips arranged in shapes such as loops, spirals, and meshes. The vias1805 carrying the power feed lines to the antenna may pass through theground plane. In some embodiments, the ground plane may be electricallyconnected to the antenna. In some embodiments, the ground plane may notbe electrically connected to the antenna 1804. For such implementations,an insulation area to insulate the vias 1805 from the ground plane maybe constructed between the vias 1805 and the ground plane. In someembodiments, the ground plane may act as a reflector of theelectromagnetic waves generated by the antenna 1804. In other words, theground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 1800 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 1804 from ortowards the top surface 1801. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface.

FIG. 19 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 1900, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 1900 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 1900 may be a part of or associated with apower receiver. The power transfer system 1900 may comprise a housingdefined by a top surface 1901, a bottom surface (not shown), andsidewalls 1903. In some embodiments, the housing may be constructed of amaterial creating minimal obstructions for electromagnetic waves to passthrough. In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 1901may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 1903 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 1907 may be disposed within a space defined between the topsurface 1901, sidewalls 1903, and the bottom surface 1902. In someembodiments, the power transfer system 1900 may not include a housingand the substrate 1907 may include the top surface 1901, sidewalls 1903,and the bottom surface 1902. The substrate 1907 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may generate radiation, andmay act as thin reflectors.

An antenna 1904 may be constructed on or below the top surface 1901.When the power transfer system 1900 is a part of or associated with apower transmitter, the antenna 1904 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system1900 is a part of or associated with a power receiver, the antenna 1904may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 1900 may operate as a transceiver and theantenna 1904 may both transmit and receive electromagnetic waves. Theantenna 1904 may be constructed from materials such as metals, alloys,and composites. For example, the antenna 1904 may be made of copper orcopper alloys. The antenna 1904 may be constructed to have differentshapes based on the power transfer requirements. In the exemplary system1900 shown in FIG. 19, the antenna 1904 is constructed in a shape of aloop including loop segments 1910 which are disposed close to eachother. The currents flowing through the neighboring loop segments 1910may be in opposite directions. For example, if the current in a firstloop segment 1910 a is flowing from left to right of FIG. 19, thecurrent in a second loop segment 1910 b may be flowing from right toleft. The opposite flow of the current results in mutual cancellation ofthe electromagnetic radiation the far field of the power transfer system1900. Therefore, there may be no leakage of power in the far field ofthe power transfer system 1900. Such cancellation, however, may notoccur in a near-field active zone of the power transfer system 1900,where the transfer of power may occur.

The power transfer system 1900 may include a ground plane (not shown) ator above the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, metamaterials, and composites. In an embodiment,the ground plane may be formed by copper or a copper alloy. In someembodiments, the ground plane may be constructed of a solid sheet ofmaterial. In other embodiments, the ground plane may be constructedusing material strips arranged in shapes such as loops, spirals, andmeshes. The vias 1905 carrying the power feed lines (not shown) to theantenna may pass through the ground plane. The power feed lines mayprovide current to the antenna 1904. In some embodiments, the groundplane 106 may be electrically connected to the antenna. In someembodiments, the ground plane may not be electrically connected to theantenna 1904. For such implementations, an insulation area to insulatethe vias 1905 from the ground plane may be constructed between the vias305 and the ground plane. In some embodiments, the ground plane may actas a reflector of the electromagnetic waves generated by the antenna1904. In other words, the ground plane may not allow electromagnetictransmission beyond the bottom surface of the power transfer system 300by cancelling and/or reflecting the transmission image formed beyond thebottom surface. Reflecting the electromagnetic waves by the ground planemay reinforce the electromagnetic waves transmitted by the antenna 1904from or towards the top surface 1901. Therefore, there may be no leakageof electromagnetic power from the bottom surface.

FIG. 20 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 2000, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 2000 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 2000 may be a part of or associated with apower receiver. In other embodiments, the power transfer system 2000 maybe a part of or associated with a transceiver. The power transfer system2000 may comprise a housing defined by a top surface 2001, a bottomsurface (not shown), and sidewalls 2003. In some embodiments, thehousing may be constructed of a material creating minimal obstructionsfor electromagnetic waves to pass through. In other embodiments,different portions of the housing may be constructed with materialshaving different electromagnetic properties such as permeability andpermittivity. For example, the top surface 2001 may allowelectromagnetic waves to pass through with minimal obstruction while thesidewalls 2003 may obstruct electromagnetic waves by attenuation,absorption, reflection, or other techniques known in the art.

A substrate 2007 may be disposed within a space defined between the topsurface 2001, sidewalls 2003, and the bottom surface 2002. In someembodiments, the power transfer system 2000 may not include a housingand the substrate 2007 may include the top surface 2001, sidewalls 2003,and the bottom surface 2002. The substrate 2007 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting cmTent, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thin reflectors.

An antenna 2004 may be constructed on or below the top surface 2001.When the power transfer system 2000 is a part of or associated with apower transmitter, the antenna 2004 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system2000 is a part of or associated with a power receiver, the antenna 2004may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 2000 may operate as a transceiver and theantenna 2004 may both transmit and receive electromagnetic waves. Thepower feed lines (not shown) to the antenna 2004 may be carried by thevias 2005. The power feed lines may provide current to the antenna 2004.The antenna 2004 may be constructed from materials such as metals,alloys, metamaterials, and composites. For example, the antenna 2004 maybe made of copper or copper alloys. The antenna 2004 may be constructedto have different shapes based on the power transfer requirements. Inthe exemplary system 2000 shown in FIG. 20, the antenna 2004 isconstructed in a shape of concentric loops including antenna segments2010 which are disposed close to each other. As shown in FIG. 20, asingle concentric loop may include two of the antenna segments 2010. Forexample, the innermost loop may include a first antenna segment 2010 cto the right of an imaginary line 2012 roughly dividing the loops intotwo halves, and a corresponding second antenna segment 2010 c′ to theleft of the imaginary line 2012. The currents flowing through theneighboring antenna segments 2010 may be in opposite directions. Forexample, if the current in the antenna segments 2010 a′, 2010 b′, 2010c′ is flowing from left to right of FIG. 20, the current in each of theantenna segments 2010 a, 2010 b, 2010 c may be flowing from right toleft. The opposite flow of the current results in mutual cancellation ofthe electromagnetic radiation at the far field of the power transfersystem 2000. Therefore, there may be no transfer of power to the farfield of the power transfer system 2000. Such cancellation, however, maynot occur in a near-field active zone of the power transfer system 2000,where the transfer of power may occur. One ordinarily skilled in the artwill appreciate the cancellation of electromagnetic radiation in the farfield and absence of such cancellation in the near-field is dictated byone or more solutions of Maxwell's equations for time-varying electricand magnetic fields generated by the currents flowing in oppositedirections. One ordinarily skilled in the art should further appreciatethe near field active zone is defined by the presence of electromagneticpower in the immediate vicinity of the power transfer system 2000.

The power transfer system 2000 may include a ground plane (not shown) ator above the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, and composites. In an embodiment, the groundplane may be formed by copper or a copper alloy. In some embodiments,the ground plane may be constructed of a solid sheet of material. Inother embodiments, the ground plane may be constructed using materialstrips arranged in shapes such as loops, spirals, and meshes. The vias2005 carrying the power feed lines to the antenna may pass through theground plane. In some embodiments, the ground plane may be electricallyconnected to the antenna. In some embodiments, the ground plane may notbe electrically connected to the antenna 2004. For such implementations,an insulation area to insulate the vias 2005 from the ground plane maybe constructed between the vias 2005 and the ground plane. In someembodiments, the ground plane may act as a reflector of theelectromagnetic waves generated by the antenna 2004. In other words, theground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 2000 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 2004 from ortowards the top surface 2001. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface.

FIG. 21 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 2100, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 2100 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 2100 may be a part of or associated with apower receiver. The power transfer system 2100 may comprise a housingdefined by a top surface 2101, a bottom surface (not shown), andsidewalls 2103. In some embodiments, the housing may be constructed of amaterial creating minimal obstructions for electromagnetic waves to passthrough. In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 2101may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 2103 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 2107 may be disposed within a space defined between the topsurface 2101, sidewalls 2103, and the bottom surface 2102. In someembodiments, the power transfer system 2100 may not include a housingand the substrate 2107 may include the top surface 2101, sidewalls 2103,and the bottom surface 2102. The substrate 2107 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thin reflectors.

An antenna 2104 may be constructed on or below the top surface 2101.When the power transfer system 2100 is a part of or associated with apower transmitter, the antenna 2104 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system2100 is a part of or associated with a power receiver, the antenna 2104may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 2100 may operate as a transceiver and theantenna 2104 may both transmit and receive electromagnetic waves. Theantenna 2104 may be constructed from materials such as metals, alloys,and composites. For example, the antenna 2104 may be made of copper orcopper alloys. The antenna 2104 may be constructed to have differentshapes based on the power transfer requirements. In the exemplary system2100 shown in FIG. 21, the antenna 2104 is constructed in a shape of amonopole. A via 2105 may carry a power feed line (not shown) to theantenna 2104. The power feed line may provide current to the antenna2104.

The power transfer system 2100 may include a ground plane (not shown) ator above the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, and composites. In an embodiment, the groundplane may be formed by copper or a copper alloy. In some embodiments,the ground plane may be constructed of a solid sheet of material. Inother embodiments, the ground plane may be constructed using materialstrips arranged in shapes such as loops, spirals, and meshes. The via2105 carrying the power feed line to the antenna 2104 may pass throughthe ground plane. In some embodiments, the ground plane may beelectrically connected to the antenna. In some embodiments, the groundplane may not be electrically connected to the antenna 2104. For suchimplementations, an insulation area to insulate the via 2105 from theground plane may be constructed between the via 2105 and the groundplane. In some embodiments, the ground plane may act as a reflector ofthe electromagnetic waves generated by the antenna 2104. In other words,the ground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 2100 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 2104 from ortowards the top surface 2101. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface.

FIG. 22 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 2200, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 2200 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 2200 may be a part of or associated with apower receiver. The power transfer system 2200 may comprise a housingdefined by a top surface 2201, a bottom surface (not shown), andsidewalls 2203. In some embodiments, the housing may be constructed of amaterial creating minimal obstructions for electromagnetic waves to passthrough. In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 2201may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 2203 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 2207 may be disposed within a space defined between the topsurface 2201, sidewalls 2203, and the bottom surface 2202. In someembodiments, the power transfer system 2200 may not include a housingand the substrate 2207 may include the top surface 2201, sidewalls 2203,and the bottom surface 2202. The substrate 2207 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thin reflectors.

An antenna 2204 may be constructed on or below the top surface 2201.When the power transfer system 2200 is a part of or associated with apower transmitter, the antenna 2204 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system2200 is a part of or associated with a power receiver, the antenna 2204may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 2200 may operate as a transceiver and theantenna 2204 may both transmit and receive electromagnetic waves. Theantenna 2204 may be constructed from materials such as metals, alloys,and composites. For example, the antenna 2204 may be made of copper orcopper alloys. A via 2205 may carry a power feed line (not shown) to theantenna. The power feed line may provide current to the antenna 2204.The antenna 2204 may be constructed to have different shapes based onthe power transfer requirements. In the exemplary system 2200 shown inFIG. 22, the antenna 2204 is constructed in a shape of a monopoleincluding antenna segments 2210 placed close to each other. The currentsflowing through the neighboring antenna segments 2210 may be in oppositedirections. For example, if the current in the antenna segment 2210 b isflowing from left to right of FIG. 22, the current each of the antennasegments 2210 a, 2210 c may be flowing from right to left. The oppositeflow of the current results in mutual cancellation of theelectromagnetic radiation in the far field of the power transfer system2200. Therefore, there may be no transfer of power in the far field ofthe power transfer system 2200. Such cancellation, however, may notoccur in a near-field active zone of the power transfer system 2200,where the transfer of power may occur. One ordinarily skilled in the artwill appreciate the cancellation of electromagnetic radiation in the farfield and absence of such cancellation in the near-field is dictated byone or more solutions of Maxwell's equations for time-varying electricand magnetic fields generated by the currents flowing in oppositedirections. One ordinarily skilled in the art should further appreciatethe near field active zone is defined by the presence of electromagneticpower in the immediate vicinity of the power transfer system 2200. Thepower transfer system 2200 may include a ground plane (not shown) at orabove the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, and composites. In an embodiment, the groundplane may be formed by copper or a copper alloy. In some embodiments,the ground plane may be constructed of a solid sheet of material. Inother embodiments, the ground plane may be constructed using materialstrips arranged in shapes such as loops, spirals, and meshes. The via2205 carrying the power feed line to the antenna 2204 may pass throughthe ground plane. In some embodiments, the ground plane may beelectrically connected to the antenna. In some embodiments, the groundplane may not be electrically connected to the antenna 2204. For suchimplementations, an insulation area to insulate the via 2205 from theground plane may be constructed between the via 2205 and the groundplane. In some embodiments, the ground plane may act as a reflector ofthe electromagnetic waves generated by the antenna 2204. In other words,the ground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 2200 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 2204 from ortowards the top surface 2201. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface.

FIG. 23 schematically illustrates a top perspective view of an exemplarynear-field power transfer system 2300, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 2300 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 2300 may be a part of or associated with apower receiver. The power transfer system 2300 may comprise a housingdefined by a top surface 2301, a bottom surface (not shown), andsidewalls 2303. In some embodiments, the housing may be constructed of amaterial creating minimal obstructions for electromagnetic waves to passthrough. In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 2301may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 2303 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 2307 may be disposed within a space defined between the topsurface 2301, sidewalls 2303, and the bottom surface 2302. In someembodiments, the power transfer system 2300 may not include a housingand the substrate 2307 may include the top surface 2301, sidewalls 2303,and the bottom surface 2302. The substrate 2307 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thin reflectors.

An antenna 2304 may be constructed on or below the top surface 2301.When the power transfer system 2300 is a part of or associated with apower transmitter, the antenna 2304 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system2300 is a part of or associated with a power receiver, the antenna 2304may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 2300 may operate as a transceiver and theantenna 2304 may both transmit and receive electromagnetic waves. Theantenna 2304 may be constructed from materials such as metals, alloys,and composites. For example, the antenna 2304 may be made of copper orcopper alloys. The antenna 2304 may be constructed to have differentshapes based on the power transfer requirements. In the exemplary system2300 shown in FIG. 23, the antenna 2304 is constructed as a hybriddipoles comprising a first spiral pole 2320 a and a second spiral pole2320 b. A first power feed line supplying current to the first spiralpole 2320 a may be provided through a first via 2305 a and a secondpower feed supplying current the second spiral pole 2320 b may beprovided through a second via 2305 b. The antenna segments in each ofthe spiral poles 2320 may mutually cancel the electromagnetic radiationin the far field generated by the spiral dipoles 2320 thereby reducingthe transfer of power to the far field. For example, the antennasegments in the first spiral pole 2320 a may cancel the far fieldelectromagnetic radiation generated by each other. Additionally, or inthe alternative, the far field radiation generated by one or moreantenna segments of the first spiral pole 2320 a may be cancelled by thefar field radiation generated by one or more antenna segments of thesecond spiral pole 2320 b. One ordinarily skilled in the art willappreciate the cancellation of electromagnetic radiation in the farfield and absence of such cancellation in the near-field is dictated byone or more solutions of Maxwell's equations for time-varying electricand magnetic fields generated by the currents flowing in oppositedirections.

The power transfer system 2300 may include a ground plane (not shown) ator above the bottom surface. The ground plane may be formed by materialssuch as metal, alloys, and composites. In an embodiment, the groundplane may be formed by copper or a copper alloy. In some embodiments,the ground plane may be constructed of a solid sheet of material. Inother embodiments, the ground plane may be constructed using materialstrips arranged in shapes such as loops, spirals, and meshes. The vias2305 carrying the power feed lines to the antenna may pass through theground plane. In some embodiments, the ground plane may be electricallyconnected to the antenna. In some embodiments, the ground plane may notbe electrically connected to the antenna 2304. For such implementations,an insulation area to insulate the vias 2305 from the ground plane maybe constructed between the vias 2305 and the ground plane. In someembodiments, the ground plane may act as a reflector of theelectromagnetic waves generated by the antenna 2304. In other words, theground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 2300 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antenna 2304 from ortowards the top surface 2301. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface.

The hybrid antenna 2304 may be required for wideband and/or multibanddesigns. For example, a non-hybrid structure may be highly efficient ata first frequency and at a first distance between the transmitter andthe receiver, but may be at inefficient other frequencies and distances.Incorporating more complex structure such as a hybrid antenna 2304 mayallow for higher efficiencies along a range of frequencies anddistances.

FIG. 24A and FIG. 24B schematically illustrate a top perspective viewand a side perspective view respectively of an exemplary near-fieldpower transfer system 2400, according to an embodiment of thedisclosure. In some embodiments, the power transfer system 2400 may be apart of or associated with a power transmitter. In other embodiments,the power transfer system 100 may be a part of or associated with apower receiver. The power transfer system 2400 may comprise a housingdefined by a top surface 2401, a bottom surface 2402, and sidewalls2403. In some embodiments, the housing may be constructed of a materialcreating minimal obstructions for electromagnetic waves to pass through.In other embodiments, different portions of the housing may beconstructed with materials having different electromagnetic propertiessuch as permeability and permittivity. For example, the top surface 2401may allow electromagnetic waves to pass through with minimal obstructionwhile the sidewalls 2403 may obstruct electromagnetic waves byattenuation, absorption, reflection, or other techniques known in theart.

A substrate 2407 may be disposed within a space defined between the topsurface 2401, sidewalls 2403, and the bottom surface 2402. In someembodiments, the power transfer system 2400 may not include a housingand the substrate 2407 may include the top surface 2401, sidewalls 2403,and the bottom surface 2402. The substrate 2407 may comprise anymaterial capable of insulating, reflecting, absorbing, or otherwisehousing electrical lines conducting current, such as metamaterials. Themetamaterials may be a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. The metamaterialsdisclosed herein may receive radiation or may transmit radiation, andmay act as thin reflectors.

The power transfer system may include hierarchical antennas 2404 thatmay be constructed on or below the top surface 2401. When the powertransfer system 2400 is a part of or associated with a powertransmitter, the antennas 2404 may be used for transmittingelectromagnetic waves. Alternatively, when the power transfer system2400 is a part of or associated with a power receiver, the antennas 2404may be used for receiving electromagnetic waves. In some embodiments,the power transfer system 2400 may operate as a transceiver and theantennas 2404 may both transmit and receive electromagnetic waves. Theantennas 2404 may be constructed from materials such as metals, alloys,and composites. For example, the antennas 2404 may be made of copper orcopper alloys. The antennas 2404 may be constructed to have differentshapes based on the power transfer requirements. In the exemplary system2400 shown in FIG. 24A and FIG. 24B, the antennas 2404 are constructedin a hierarchical spiral structure with a level zero hierarchicalantenna 2404 a and a level one hierarchical antenna 2404 b. Each of thehierarchical antennas 2404 may include antenna segments, wherein antennasegments have currents flowing in the opposite directions to cancel outthe far field radiations. For example, the antenna segments in the levelzero hierarchical antenna 2404 a may cancel the far fieldelectromagnetic radiation generated by each other. Additionally, or inthe alternative, the far field radiation generated by one or moreantenna segments of the level zero hierarchical antenna 2404 a may becancelled by the far field radiation generated by one or more antennasegments of the level one hierarchical antenna 2404 b. A power feed line(not shown) to the antennas is carried through a via 2405. The powerfeed line may supply current to the antenna 2404.

The power transfer system 2400 may include a ground plane 2406 at orabove the bottom surface 2402. The ground plane 2406 may be formed bymaterials such as metal, alloys, and composites. In an embodiment, theground plane 2406 may be formed by copper or a copper alloy. In someembodiments, the ground plane 2406 may be constructed of a solid sheetof material. In other embodiments, the ground plane 2406 may beconstructed using material strips arranged in shapes such as loops,spirals, and meshes. The via 2405 carrying a power feed line to theantenna may pass through the ground plane 2406. In some embodiments, theground plane 2406 may be electrically connected to one or more of theantennas 2404. In some embodiments, the ground plane 2406 may not beelectrically connected to the antennas 2404. For such implementations,an insulation area 2408 to insulate the via 2405 from the ground plane2406 may be constructed between the via 2405 and the ground plane 2406.In some embodiments, the ground plane 2406 may act as a reflector of theelectromagnetic waves generated by the antennas 2404. In other words,the ground plane may not allow electromagnetic transmission beyond thebottom surface of the power transfer system 2400 by cancelling and/orreflecting the transmission image formed beyond the bottom surface.Reflecting the electromagnetic waves by the ground plane may reinforcethe electromagnetic waves transmitted by the antennas 2404 from ortowards the top surface 2401. Therefore, there may be no leakage ofelectromagnetic power from the bottom surface 2402. In some embodiments,there may be multiple ground planes, with a ground plane for each of thehierarchical antennas 2404. In some embodiments, the hierarchicalantennas have different power feed lines carried through multiple vias.

The hierarchical antennas 2404 may be required for wideband and/ormultiband designs. For example, a non-hierarchical structure may behighly efficient at a first frequency and at a first distance betweenthe transmitter and the receiver, but may be inefficient at otherfrequencies and distances. Incorporating more complex structures, suchas hierarchical antennas 2404, may allow for higher efficiencies along arange of frequencies and distances.

FIGS. 25A-25H illustrate various views of a representative near-fieldantenna 2500 in accordance with some embodiments. It is noted that therepresentative near-field antenna 2500, and its various components, maynot be drawn to scale. Moreover, while some example features areillustrated, various other features have not been illustrated for thesake of brevity and so as not to obscure pertinent aspects of theexample implementations disclosed herein. In some instances, thenear-field antenna 2500 is referred to as a “quad-pol antenna element.”In some embodiments, the near-field antenna 2500 is part of the chargingpad 100, e.g., one or more of the near-field antennas 2500 are includedin each of the antenna zones 290 (FIG. 1B). In some embodiments, thenear-field antennas 2500 are the only antennas included in each of theantenna zones while, in other embodiments, the near-field antennas 2500can be included in respective antenna zones along with other antennasdescribed herein. In still other embodiments, the near-field antennas2500 can be included as the only antennas in certain of the antennazones, while other antenna zones may include only other types ofantennas that are described herein.

FIG. 25A shows an isometric view of the near-field antenna 2500 inaccordance with some embodiments. As shown, the near-field antenna 2500includes a substrate 2506 offset from a reflector 2504 (e.g., offsetalong the z-axis), and thus a gap is formed between the reflector 2504and substrate 2506. In such an arrangement, the reflector 2504 defines afirst plane (e.g., a first horizontal plane: the bottom surface) and thesubstrate 2506 defines a second plane (e.g., a second horizontal plane:the top surface) that is offset from the first plane. In someembodiments, the substrate 2506 is made from a dielectric, while inother embodiments the substrate 2506 is made from other materialscapable of insulating, reflecting, absorbing, or otherwise housingelectrical lines conducting current, such as metamaterials.Metamaterials are a broad class of synthetic materials that areengineered to yield desirable magnetic permeability and electricalpermittivity. At least one of the magnetic permeability and electricalpermittivity may be based upon power-transfer requirements, and/orcompliance constraints for government regulations. In variousembodiments, the metamaterials disclosed herein can be used to receiveradiation, transmit radiation, and/or as reflectors.

In some embodiments, the reflector 2504 is a metal sheet (e.g., copper,copper alloy, or the like) while in other embodiments the reflector 2504is a metamaterial. The reflector 2504 is configured to reflect someelectromagnetic signals radiated by the near-field antenna 2500. Inother words, the reflector 2504 may not allow electromagnetictransmission beyond the bottom surface of the near-field antenna 2500 byreflecting the electromagnetic signals radiated by the near-fieldantenna 2500. Additionally, reflecting the electromagnetic signals bythe reflector 2504 can redirect some of the electromagnetic signalstransmitted by antenna elements of the near-field antenna 2500 from ortowards the substrate 2506. In some instances, the reflector 2504reduces far-field gain of the near-field antenna 2500. In someembodiments, the reflector 2504 also cancels some electromagneticsignals radiated by the near-field antenna 2500.

The substrate 2506 further includes four distinct coplanar antennaelements (also referred to herein as “radiating elements”), where eachof the four distinct antenna elements follows a respective meanderingpattern. The four distinct coplanar antenna elements may each occupy adistinct quadrant of the substrate. The coplanar antenna elements may beembedded in the substrate 2506, such that respective first surfaces ofthe coplanar antenna elements are coplanar with a top surface of thesubstrate 2506, and respective second surfaces, opposite the respectivefirst surfaces, of the coplanar antenna elements are coplanar with abottom surface of the substrate 2506. The respective meandering patternsare used to increase an effective length of each of the four distinctcoplanar antenna elements, thus resulting in a lower resonant frequencyof the antenna 2500 while reducing an overall size of the antenna 2500.

In some embodiments, the respective meandering patterns are all the samewhile, in other embodiments, one or more of the respective meanderingpatterns differ. Each of the four distinct coplanar antenna elementsincludes a plurality of continuous (and/or contiguous) segments, whichare discussed below with reference to FIG. 25F. In some embodiments (notshown), a shape of each segment in the plurality of segments issubstantially the same (e.g., each is rectangular or some other shape).Alternatively, in some other embodiments, a shape of at least onesegment in the plurality of segments differs from shapes of othersegments in the plurality of segments. It is noted that variouscombinations of shapes can be used to form the segments of a respectiveantenna element, and the shapes shown in FIG. 25A are merelyillustrative examples. Further, in some embodiments, the substrate 2506is not included and the four distinct coplanar antenna elements are madefrom stamped metal (i.e., the radiating elements are sitting in openspace above the reflector 2504).

The four distinct coplanar antenna elements are shown in FIG. 25A as afirst radiating element 2502-A, a second radiating element 2502-B, athird radiating element 2502-C, and a fourth radiating element 2502-D.The first radiating element 2502-A and the second radiating element2502-B together compose (i.e., form) a first dipole antenna 2501-Apositioned along (e.g., center on) a first axis (e.g., the X-axis). Inother words, the first radiating element 2502-A is a first pole of thefirst dipole antenna 2501-A and the second radiating element 2502-B is asecond pole of the first dipole antenna 2501-A. The first dipole antenna2501-A is indicated by the dashed line.

In addition, the third radiating element 2502-C and the fourth radiatingelement 2502-D together compose (i.e., form) a second dipole antenna2501-B positioned along a second axis (e.g., the Y-axis) perpendicularto the first axis. In other words, the third radiating element 2502-C isa first pole of the second dipole antenna 2501-B and the fourthradiating element 2502-D is a second pole of the second dipole antenna2501-B. The second dipole antenna 2501-B is indicated by thedashed-dotted line.

FIG. 25B shows another isometric view (e.g., isometric underneath view)of the near-field antenna 2500 in accordance with some embodiments. Forease of illustration, the reflector 2504 is not shown in FIG. 25B.

As shown, the near-field antenna 2500 further includes a first feed2508-A and a second feed 2508-B attached to a central region of thesubstrate 2504. The first feed 2508-A is connected to the first andsecond radiating elements 2502-A, 2502-B forming the first dipoleantenna 2501-A. More specifically, the first feed 2508-A is connected tothe second radiating element 2502-B via a connector 2512-A (FIG. 25C)and to the first radiating element 2502-A via an intra-dipole connector2510-A. The first feed 2508-A is configured to supply electromagneticsignals that originate from a power amplifier (e.g., power amplifier108, FIG. 26) to the first and second radiating elements 2502-A, 2502-B.

The second feed 2508-B is connected to the third and fourth radiatingelements 2502-C, 2502-D forming the second dipole antenna 2501-B. Morespecifically, the second feed 2508-B is connected to the fourthradiating element 2502-D via a connector 2512-B (FIG. 25C) and to thethird radiating element 2502-C via an intra-dipole connector 2510-B. Thesecond feed 2508-B is configured to supply electromagnetic signals thatoriginate from the power amplifier to the third and fourth radiatingelements 2502-C, 2502-D. The four radiating elements are configured toradiate the provided electromagnetic signals (e.g., radio frequencypower waves), which are used to power or charge awireless-power-receiving device.

In some embodiments, as explained below in detail, the four radiatingelements do not radiate at the same time. Instead, based on informationabout a wireless-power receiving device, either the first dipole antenna2501-A is supplied the electromagnetic signals or the second dipoleantenna 2501-B is supplied electromagnetic signals.

The electromagnetic signals radiated by the first dipole antenna 2501-Ahave a first polarization and the electromagnetic signals radiated bythe second dipole antenna 2501-B have a second polarizationperpendicular to the first polarization. The differences in polarizationare attributable, at least in part, to the orientations of the first andsecond dipole antennas 2501-A, 2501-B. For example, the first dipoleantenna 2501-A is positioned along the first axis (e.g., the X-axis) andthe second dipole antenna 2501-B is positioned along the second axis(e.g., the Y-axis), which is perpendicular to the first axis. Thus, insome instances, the electromagnetic signals are fed to the dipoleantenna whose polarization matches a polarization of apower-receiving-antenna of a wireless-power-receiving device. A processfor selectively coupling one of the dipole antennas to anelectromagnetic signals feeding source (i.e., a power amplifier 108) isdescribed below in method 3000 (FIG. 30).

For ease of discussion below, the substrate 2506 and the radiatingelements 2502-A-2502-D are referred to collectively as the “radiator2507” when appropriate.

FIGS. 25C-25D show different side views of the near-field antenna 2500,where the side view in FIG. 25D is rotated 90 degrees relative to theside view in FIG. 25C. In certain embodiments or circumstances, thefirst feed 2508-A is connected to the second radiating element 2502-B bythe connector 2512-A and to the first radiating element 2502-A by theintra-dipole connector 2510-A (FIG. 25B also shows the intra-dipoleconnector 2510-A). In certain embodiments or circumstances, the secondfeed 2508-B is connected to the fourth radiating element 2502-B by theconnector 2512-B and to the third radiating element 2502-C by theintra-dipole connector 2510-B (FIG. 25B also shows the intra-dipoleconnector 2510-B).

FIG. 25E shows another side view of the near-field antenna 2500 inaccordance with some embodiments. As shown, the first and second feeds2508-A, 2508-B are substantially perpendicular to the radiator 2507. Forexample, each of the feeds 2508-A, 2508-B is disposed along a respectivevertical axis while the antenna 2507 is disposed along a horizontalaxis/plane. Further, the first and second feeds 2508-A, 2508-B areconnected at a first end to the antenna 2507, and are connected at asecond end, opposite the first end, to a printed circuit board 2514 anda ground plane 2516. In some embodiments, the printed circuit board 2514and the ground plate 2516 compose the reflector 2504. Alternatively, insome embodiments, the reflector 2504 is a distinct component, which isoffset from the printed circuit board 2514 and the ground plane 2516(e.g., positioned between the antenna 2507 and the printed circuit board2514). In this arrangement, the reflector 2504 may define openings (notshown), and the first and second feeds 2508-A, 2508-B may pass throughsaid openings.

As shown in the magnified view 2520, the first feed 2508-A includes afeedline 2524-A (e.g., a conductive metal line) housed (i.e.,surrounded) by a shield 2522-A. The feedline 2524-A is connected tometal traces (e.g., communication buses 208, FIG. 26) of the printedcircuit board 2514 by a metal deposit 2526-A. Further, the shield 2522-Acontacts the ground plane 2516, thereby grounding the first dipole2501-A.

Similarly, the second feed 2508-B includes a feedline 2524-B housed by ashield 2522-B. The feedline 2524-B is connected to metal traces (notshown) of the printed circuit board 2514 by a metal deposit 2526-B.Further, the shield 2522-B contacts the ground plane 2516, therebygrounding the second dipole 2501-B. As explained below with reference toFIG. 26, the metal traces of the printed circuit board 2514 may beconnected to one or more additional components (not shown in FIGS.25A-25H) of the near-field antenna 2500, including one or more poweramplifiers 108, an impedance-adjusting component 2620, and a switch 2630(also referred to herein as “switch circuitry”).

Although not shown in FIG. 25E, a dielectric may separate the feedlinefrom the shield in each feed (e.g., electrically isolate the twocomponents). Additionally, another dielectric can surround the shield ineach feed to protect the shield (i.e., the first and second feeds2508-A, 2508-B may be coaxial cables). It is also noted that theparticular shapes of the metal deposits 2526-A, 2526-B can vary incertain embodiments, and the shapes shown in FIG. 25E are examples usedfor ease of illustration.

FIG. 25F shows a representative radiating element 2550 following ameandering pattern in accordance with some embodiments. As shown, therepresentative radiating element 2550 includes: (i) a first plurality ofsegments 2560-A-2560-D, and (ii) a second plurality of segments2562-A-2562-C interspersed between the first plurality of segments2560-A-2560-D (separated by dashed lines). In some embodiments, thefirst plurality of segments 2560-A-2560-D and the second plurality ofsegments 2562-A-2562-C are continuous segments. Alternatively, in someother embodiments, the first plurality of segments 2560-A-2560-D and thesecond plurality of segments 2562-A-2562-C are contiguous segments(e.g., ends of neighboring segments abut one another). The illustratedboundaries (e.g., the dashed lines) separating the segments in FIG. 25Fare merely one example set of boundaries that is used for illustrativepurposes only, and one of skill in the art will appreciate (upon readingthis disclosure) that other boundaries (and segment delineations) arewithin the scope of this disclosure.

As shown, lengths of segments in the first plurality of segments2560-A-2560-D increase from a first end portion 2564 of the radiatingelement 2550 to a second end portion 2566 of the radiating element 2550.In some embodiments, while not shown, lengths of segments in the secondplurality of segments 2562-A-2562-C increase from the first end portion2564 of the radiating element 2550 to the second end portion 2566 of theradiating element 2550. Alternatively, in some other embodiments,lengths of segments in the second plurality of segments 2562-A-2562-Cremain substantially the same from the first end portion 2564 of theradiating element 2550 to the second end portion 2566 of the radiatingelement 2550. In the illustrated embodiment, the lengths of the firstplurality of segments 2560-A-2560-D are different from the lengths ofthe second plurality of segments 2562-A-2562-C. Further, the lengths ofthe first plurality of segments 2560-A-2560-D toward the second endportion 2566 of the radiating element 2550 are greater than the lengthsof the second plurality of segments 2562-A-2562-C toward the second endportion 2566 of the radiating element 2550.

In some embodiments, the shape of the radiating element provides certainimportant advantages. For example, the specific shape of therepresentative radiating element 2550 shown in FIG. 25F provides thefollowing advantages: (i) the shape allows twoperpendicularly-positioned dipoles to fit in a small area and occupyfour quadrants of the substrate 2506 where each pair of quadrants isperpendicular to each other, and (ii) the width and gaps betweensegments of neighboring radiating elements (i.e., spacing betweenquadrants) can be varied to tune the near-field antenna 2500 to adesired frequency, while still maintaining the radiating elements'miniaturized form-factor. To illustrate numeral (i), with reference toFIG. 25A, the first and second radiating elements 2502-A, 2502-B occupya first pair of quadrants that include sides of the near-field antennathat are along the Y-axis. Further, the third and fourth radiatingelements 2502-C, 2502-D occupy a second pair of quadrants that includesides of the near-field antenna that are along the X-axis. Accordingly,the first and second pairs of quadrants of the substrate 2506 includesides of the NF antenna that are perpendicular to each other (e.g., thisfeature is facilitated, in part, by a width of each radiating elementincreasing from a central portion of the near-field antenna 2500 to arespective side of the near-field antenna 2500).

FIG. 25G shows a top view of the representative near-field antenna 2500in accordance with some embodiments. Dimensions of the near-fieldantenna 2500 can effect an operating frequency of the near-field antenna2500, radiation efficiency of the near-field antenna 2500, and aresulting radiation pattern (e.g., radiation pattern 2800, FIG. 28A)produced by the near-field antenna 2500, among other characteristics ofthe NF antenna 2500. As one example, the near-field antenna 2500, whenoperating at approximately 918 MHz has the following dimensions(approximately): D1=9.3 mm, D2=12.7 mm, D3=23.7 mm, D4=27 mm, D5=32 mm,D6=37.5 mm, D7=10.6 mm, D8=5.1 mm, D9=10.6 mm, D10=5.5 mm, D11=2.1 mm,and D12=28 mm. Further, the reflector 2504 may have a width of 65 mm, aheight of 65 mm, and a thickness of 0.25 mm.

FIG. 25H shows another top view of the representative near-field antenna2500 in accordance with some embodiments. As shown, the four distinctcoplanar antenna elements each occupy a distinct quadrant of thesubstrate 2506 (e.g., occupy one of the quadrants 2570-A through 2570-D,demarcated by the dash-dotted lines). Further, (i) a first end portion2564 of the respective meandering pattern followed by each of the fourdistinct antenna elements borders a central portion 2574 (dotted line)of the near-field antenna 2500, and (ii) a second end portion 2566 ofthe respective meandering pattern followed by each of the four distinctantenna elements borders one of the edges 2572-A-2572-D of thenear-field antenna 2500. In such an arrangement, a longest dimension ofthe respective meandering pattern followed by each of the four distinctantenna elements (e.g., segment 2560-D) is closer to a distinct edge2572 of the near-field antenna than to the central portion 2574 of thenear-field antenna 2500. Moreover, a shortest dimension of therespective meandering pattern followed by each of the four distinctantenna elements is closer to the central portion 2574 of the near-fieldantenna 2500 than a distinct edge 2572 of the near-field antenna 2500.Thus, a width of each of the four distinct antenna elements increases,in a meandering fashion, from the central portion 2574 of the near-fieldantenna 2500 to a respective edge 2572 of the near-field antenna 2500.Furthermore, in some embodiments, the longest dimension of therespective meandering pattern parallels the distinct edge 2572.

As shown in FIG. 27, the near-field antenna 2500 (when it includes areflector) creates substantially uniform radiation pattern 2700 that hasminimal far-field gain. The dimensions provided above are merely usedfor illustrative purposes, and a person of skill in the art (uponreading this disclosure) will appreciate that various other dimensionscould be used to obtain acceptable radiation properties, depending onthe circumstances.

FIG. 26 is a block diagram of a control system 2600 used for controllingoperation of certain components of the near-field antenna 2500 inaccordance with some embodiments. The control system 2600 may be anexample of the charging pad 100 (FIG. 1A), however, one or morecomponents included in the charging pad 100 are not included in thecontrol system 2600 for ease of discussion and illustration.

The control system 2600 includes an RF power transmitter integratedcircuit 160, one or more power amplifiers 108, an impedance-adjustingcomponent 2620, and the near-field antenna 2500, which includes thefirst and second dipole antennas 2501-A, 2501-B. Each of thesecomponents is described in detail above, and the impedance-adjustingcomponent 2620 is described in more detail below.

The impedance-adjusting component 2620 may be an RF termination or load,and is configured to adjust an impedance of at least one of the firstand second dipole antennas 2501-A, 2501-B. Put another way, theimpedance-adjusting component 2620 is configured to change an impedanceone of the dipole antennas, thereby creating an impedance mismatchbetween the two dipole antennas. By creating an impedance mismatchbetween the two dipole antenna, mutual coupling between the two dipoleantennas is substantially reduced. It is noted that theimpedance-adjusting component 2620 is one example of anantenna-adjusting component. Various other antenna-adjusting componentsmight be used (e.g., to change an effective length of any of theradiating elements) to adjust various other characteristics of theantenna (e.g., such as length of the respective antenna elements of eachdipole), in order to ensure that one of the two dipoles is not tuned toa transmission frequency of the other dipole.

The control system 2600 also includes a switch 2630 (also referred toherein as “switch circuitry”) having one or more switches therein (notshown). The switch 2630 is configured to switchably couple the first andsecond dipole antennas 2501-A, 2501-B to the impedance-adjustingcomponent 2620 and at least one power amplifier 108, respectively (orvice versa), in response to receiving one or more instructions in theform of electrical signals (e.g., the “Control Out” signal) from the RFpower transmitter integrated circuit 160. For example, the switch 2630may couple, via one or more switches, the first dipole antenna 2501-Awith the impedance-adjusting component 2620 and the second dipoleantenna 2501-B with at least one power amplifier 108, or vice versa.

To accomplish the switching discussed above, the switch 2630 providesdistinct signal pathways (e.g., via the one or more switches therein) tothe first and second dipole antennas 2501-A, 2501-B. Each of theswitches, once closed, creates a unique pathway between either: (i) arespective power amplifier 108 (or multiple power amplifiers 108) and arespective dipole antenna, or (ii) the impedance-adjusting component2620 and a respective dipole antenna. Put another way, some of theunique pathways through the switch 2630 are used to selectively provideRF signals to one of the dipole antennas 2501-A, 2501-B while some ofthe unique pathways through the switch 2630 are used to adjust animpedance of one of the dipole antennas 2501-A, 2501-B (i.e., detune thedipole antennas 2501-A, 2501-B). It is noted that two or more switchesof the switch circuitry may be closed at the same time, thereby creatingmultiple unique pathways to the near-field antenna 2500 that may be usedsimultaneously.

As shown, the RF power transmitter integrated circuit 160 is coupled tothe switch 2630 via busing 208. The integrated circuit 160 is configuredto control operation of the one or more switches therein (illustrated asthe “Control Out” signal in FIGS. 1A, 1C, and 26). For example, the RFpower transmitter integrated circuit 160 may close a first switch in theswitch 2630, which connects a respective power amplifier 108 with thefirst dipole antenna 2501-A, and may close a second switch in the switch2630 that connects the impedance-adjusting component 2620 with thesecond dipole antenna 2501-B, or vice versa. Moreover, the RF powertransmitter integrated circuit 160 is coupled to the one or more poweramplifiers 108 and is configured to cause generation of a suitable RFsignal (e.g., the “RF Out” signal) and cause provision of the RF signalto the one or more power amplifiers 108. The one or more poweramplifiers 108, in turn, are configured to provide the RF signal (e.g.,based on an instruction received from the RF power transmitterintegrated circuit 160) to one of the dipole antennas via the switch2630, depending on which switch (or switches) in the switch circuitry2630 is (are) closed.

In some embodiments, the RF power transmitter integrated circuit 160controller is configured to control operation of the switch 2630 and theone or more power amplifiers 108 based on one or more of: (i) a locationof a wireless-power-receiving device near (or on) the near-field antenna2500, (ii) a polarization of a power-receiving-antenna of thewireless-power-receiving device, and (iii) a spatial orientation of thewireless-power-receiving device. In some embodiments, the RF powertransmitter integrated circuit 160 receives information that allows thecircuit 160 to determine (i) the location of thewireless-power-receiving device, (ii) the polarization of thepower-receiving-antenna of the wireless-power-receiving device, and(iii) the spatial orientation of the wireless-power-receiving devicefrom the wireless-power-receiving device. For example, thewireless-power-receiving device can send one or more communicationssignals to a communication radio of the near-field antenna 2500indicating each of the above (e.g., data in the one or morecommunications signals indicates the location, polarization, and/ororientation of the wireless-power-receiving device). Further, as shownin FIG. 1A, the wireless communication component 204 (i.e., thecommunication radio of the near-field antenna 2500) is connected to theRF power transmitter integrated circuit 160. Thus, the data received bythe wireless communication component 204 can be conveyed to the RF powertransmitter integrated circuit 160.

In some embodiments, the first dipole antenna 2501-A may be configuredto radiate electromagnetic signals having a first polarization (e.g.,horizontally polarized electromagnetic signals) and the second dipoleantenna 2501-B may be configured to radiate electromagnetic signalshaving a second polarization (e.g., vertically polarized electromagneticsignals) (or vice versa). Further, if the power-receiving-antenna of thewireless-power-receiving device is configured to receive electromagneticsignals having the first polarization, then the RF power transmitterintegrated circuit 160 will connect the first dipole antenna 2501-A tothe one or more power amplifiers 108 and will connect theimpedance-adjusting component 2620 with the second dipole antenna2501-B, via the switch 2630. In this way, the electromagnetic signalsradiated by the near-field antenna 2500 will have a polarization thatmatches the polarization of the target device, thereby increasing anefficiency of energy transferred to the wireless-power-receiving device.

In some embodiments, the switch 2630 may be part of (e.g., internal to)the near-field antenna 2500. Alternatively, in some embodiments, theswitch 2630 is separate from the near-field antenna 2500 (e.g., theswitch 2630 may be a distinct component, or may be part of anothercomponent, such as the power amplifier(s) 108). It is noted that anyswitch design capable of accomplishing the above may be used.

FIG. 27 shows a radiation pattern 2700 generated by the near-fieldantenna 2500 when it does include the back reflector 2504 (i.e., theradiating antenna elements are “backed” by the metallic reflector). Theillustrated radiation pattern 2700 is generated by the near-fieldantenna 2500 when (i) the first dipole antenna 2501-A is fedelectromagnetic signals by the one or more power amplifiers 108, and(ii) the near-field antenna 2500 includes the reflector 2504. As shown,the radiation pattern 2700 has a higher concentration of EM energyproduced along the X-axis and Y-axis (and has a radiation null along theZ-axis) and forms an overall torus shape. As such, the electromagneticfield concentration stays closer to the NF antenna 2500 and far-fieldgain is minimized (e.g., the EM field concentration stays closer to theradiator 2507 and the reflector 2504, FIG. 25E). Although not shown, theradiation pattern 2700 is polarized in a direction that is aligned withthe X-axis.

Thus, by incorporating the reflector 2504, the radiation pattern 2700 isrotated 90 degrees about the X-axis relative to the radiation pattern2800 (FIG. 28A, discussed below). Additionally, by incorporating thereflector 2504, a radiation null is formed along the Z-axis, whichsubstantially reduces far-field gain, and energy radiated by thenear-field antenna 2500 is concentrated within a near-field distancefrom the near-field antenna 2500. Again, the second dipole antenna2501-B may be connected to the impedance-adjusting component 2620 whenthe first dipole antenna 2501-A is fed the electromagnetic signals.

FIG. 28A to FIG. 28C show various radiation patterns generated by anembodiment of the near-field antenna 2500 that does not include thereflector 2504. The radiation pattern 2800 illustrated in FIG. 28A isgenerated by the near-field antenna 2500 when the first dipole antenna2501-A is fed electromagnetic signals by the one or more poweramplifiers 108. As shown, the radiation pattern 2800 has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis) and forms an overall torus shape.This pattern 2800 shows that an antenna element, without the reflector,radiates outward/perpendicular to the near-field antenna 2500. Althoughnot shown, the radiation pattern 2800 is polarized in a first direction(e.g., aligned with the X-axis). Furthermore, the second dipole antenna2501-B may be connected to the impedance-adjusting component 2620 whenthe first dipole antenna 2501-A is fed the electromagnetic signals bythe one or more power amplifiers 108.

The radiation pattern 2810 illustrated in FIG. 28B is generated by thenear-field antenna 2500 when the second dipole antenna 2501-B is fedelectromagnetic signals by the one or more power amplifiers 108 (i.e.,the first dipole antenna 2501-A is not fed electromagnetic signals andinstead may be connected to the impedance-adjusting component 2620).FIG. 28B shows that the radiation pattern 2810 that has a higherconcentration of EM energy produced along the Z-axis and the Y-axis (andhas a radiation null along the X-axis), which also forms an overalltorus shape. Although not shown, the radiation pattern 2810 is polarizedin a second direction (e.g., aligned with the Y-axis). Accordingly, thefirst dipole antenna 2501-A is configured to generate a radiationpattern 2800 polarized in the first direction while the second dipoleantenna 2501-B is configured to generate a radiation pattern 2810polarized in the second direction perpendicular to the first direction.In this way, the first dipole antenna 2501-A is fed when thepolarization of the electromagnetic signals generated by the firstdipole antenna 2501-A match a polarization of a power-receiving antennaof a wireless-power-receiving device. Alternatively, the second dipoleantenna 2501-D is fed when the polarization of the electromagneticsignals generated by the second dipole antenna 2501-B match apolarization of a power-receiving antenna of a wireless-power-receivingdevice.

FIG. 28C shows a radiation pattern 2820 generated when both the firstand second dipole antennas are fed electromagnetic signals by the one ormore power amplifiers 108, and neither dipole antenna is connected tothe impedance-adjusting component 2620. As shown, the radiation pattern2820 has higher concentrations of EM energy produced along the Z-axis,X-axis and the Y-axis (and a radiation null is formed between the X-axisand the Y-axis) and forms an overall torus shape.

FIGS. 29A and 29B show concentrations of energy radiated and absorbed bydipole antennas of the near-field antenna 2500 in accordance with someembodiments.

In particular, FIG. 29A shows the resulting concentrations of energyradiated and absorbed by the dipole antennas 2501-A, 2501-B when animpedance of the first dipole antenna 2501-A substantially matches animpedance of the second dipole antenna 2501-B. FIG. 29B shows theresulting concentrations of energy radiated and absorbed by the dipoleantennas 2501-A, 2501-B of the near-field antenna 2500 when an impedanceof the first dipole antenna 2501-A differs from an impedance of thesecond dipole antenna 2501-B, which is achieved by connecting one of thedipole antennas to the impedance-adjusting component 2620. Put anotherway, the first and second dipole antennas 2501-A, 2501-B areintentionally detuned as a result of one of the dipole antennas beingconnected to the impedance-adjusting component 2620.

An absence of impedance mismatch between neighboring antenna elementsleads to substantial mutual coupling between neighboring antennaelements. “Mutual coupling” refers to energy being absorbed by oneantenna element (or one antenna dipole) when another nearby antennaelement (or antenna dipole) is radiating. Antennas (or antenna arrays)with closely spaced antenna elements typically suffer from undesiredmutual coupling between neighboring antenna elements, which limits theantenna's ability to radiated efficiency (this problem is particularlyacute when the antenna elements are placed close together and when theantenna elements are miniaturized).

For example, with reference to FIG. 29A, the second dipole antenna2501-B is fed electromagnetic signals by the one or more poweramplifiers 108, and the coloring along the second dipole antenna 2501-Brepresents different concentrations of energy radiated by the seconddipole antenna 2501-B, with reds corresponding to high concentrations,greens corresponding to medium concentrations, and blues correspondingto low concentrations. The first dipole antenna 2501-A in FIG. 29A isnot independently radiating, however, certain amounts of the energyradiated by the second dipole antenna 2501-B is absorbed at the firstdipole antenna 2501-A as a result of the mutual coupling between the twodipole antennas. Because of this mutual coupling, a radiation efficiencyof the near-field antenna 2500 is not optimized (e.g., the NF antenna2500 may only be able to transfer 50% or less of the energy it attemptsto transmit).

In contrast, with reference to FIG. 29B, the second dipole antenna2501-B is fed electromagnetic signals by the one or more poweramplifiers 108. Additionally, the first dipole antenna 2501-A is coupledto the impedance-adjusting component 2620, thereby creating anintentional impedance mismatch between the two dipole antennas. In sucha configuration, the first dipole antenna 2501-A in FIG. 29B isabsorbing far less energy radiated by the second dipole antenna 2501-Bcompared to an amount of the energy that the first dipole antenna 2501-Awas absorbing in FIG. 29A. Accordingly, a radiation efficiency of thenear-field antenna 2500 in FIG. 29B is higher (e.g., the NF antenna 2500may now be able to radiate 90% or greater of the energy it attempts totransmit) than the radiation efficiency of the near-field antenna 2500in FIG. 29A.

Method of Operation

FIG. 30 is a flow diagram showing a method 3000 of wireless powertransmission in accordance with some embodiments. Operations (e.g.,steps) of the method 3000 may be performed by a controller (e.g., RFpower transmitter integrated circuit 160, FIGS. 1A and 26) associatedwith a near-field antenna (e.g., near-field antenna 2500, FIG. 25A). Atleast some of the operations shown in FIG. 30 correspond to instructionsstored in a computer memory or computer-readable storage medium (e.g.,memory 206 of the charging pad 100, FIG. 2A).

The method 3000 includes providing (3002) a near-field antenna thatincludes a reflector (e.g., reflector 2504, FIG. 25A) and four distinctcoplanar antenna elements (e.g., radiating elements 2502-A to 2502-D,FIG. 25A) offset from the reflector. The four distinct antenna elementsfollow respective meandering patterns, such as the meandering patternshown in FIG. 25F. Furthermore, (i) two antenna elements of the fourcoplanar antenna elements form a first dipole antenna (e.g., dipoleantenna 2501-A, FIG. 25A) aligned with a first axis (e.g., X-axis, FIG.25A), and (ii) another two antenna elements (e.g., dipole antenna2501-B, FIG. 25A) of the four coplanar antenna elements form a seconddipole antenna aligned with a second axis (e.g., Y-axis, FIG. 25A)perpendicular to the first axis. In some embodiments, the respectivemeandering patterns are all the same.

In some embodiments, a first antenna element (e.g., first radiatingelement 2502-A) of the four distinct coplanar antenna elements is afirst pole of the first dipole antenna and a second antenna element(e.g., second radiating element 2502-B) of the four distinct coplanarantenna elements is a second pole of the first dipole antenna.Furthermore, a third antenna element (e.g., third radiating element2502-C) of the four distinct coplanar antenna elements may be a firstpole of the second dipole antenna and a fourth antenna element (e.g.,fourth radiating element 2502-D) of the four distinct coplanar antennaelements may be a second pole of the second dipole antenna. The twoantenna elements that form the first dipole antenna can each include twosegments that are perpendicular to the first axis, and the other twoantenna elements that form the second dipole antenna can each includetwo segments that parallel the first axis. For example, with referenceto FIG. 25A, the first and second radiating elements 2502-A, 2502-B eachincludes two segments (e.g., segments 2560-C and 2560-D, FIG. 25F) thatare perpendicular to the X-axis, and the third and fourth radiatingelements 2502-C, 2502-D each includes two segments (e.g., segments2560-C and 2560-D, FIG. 25F) that are parallel to the X-axis. In such anarrangement, the two antenna elements that form the first dipole antennaare configured to radiate electromagnetic signals having a firstpolarization, and the two antenna elements that form the second dipoleantenna are configured to radiate electromagnetic signals having asecond polarization perpendicular to the first polarization.

In some embodiments, each of the four distinct antenna elementsincludes: (i) a first plurality of segments, and (ii) a second pluralityof segments interspersed between each of the first plurality ofsegments. For example, with reference to FIG. 25G, the second pluralityof segments 2562-A-2562-C are interspersed between the first pluralityof segments 2560-A-2560-D. In such embodiments, first lengths ofsegments in the first plurality of segments increase from a first endportion of the antenna element to a second end portion of the antennaelement, as shown in FIGS. 25F and 25G. It is noted that the “first endportion” of each antenna element corresponds to the first end portion2564 illustrated in FIG. 25F, and the first end portion of each antennaelement is near a central portion 2574 (FIG. 25H) of the near-fieldantenna 2500. Furthermore, the “second end portion” of each antennaelement corresponds to the second end portion 2566 illustrated in FIG.25F, and the second end portion 2566 of each antenna element extendstowards an edge 2572 (FIG. 25H) of the near-field antenna 2500. Thus,put simply, a width of each of the four distinct antenna elementsincreases, in a meandering fashion, from a central portion of thenear-field antenna 2500 to a respective edge of the near-field antenna2500.

In some embodiments, second lengths of segments in the second pluralityof segments also increase from the first end portion of the antennaelement to the second end portion of the antenna element, while in otherembodiments the second lengths of the segments in the second pluralityof segments remain substantially the same, as shown in FIG. 25F.Additionally, the first lengths of one or more segments in the firstplurality of segments are different from the second lengths of thesegments in the second plurality of segments. In some embodiments, thefirst lengths of the first plurality of segments toward the second endportion of the antenna element are greater than the second lengths ofthe second plurality of segments toward the second end portion of theantenna element. For example, the lengths of segments 2560-C and 2560-Dare substantially longer than the lengths of segments 2562-B and 2562-C.Segments of the radiating elements are discussed in further detail abovewith reference to FIGS. 25F and 25G.

In some embodiments, a first end portion of the respective meanderingpattern followed by each of the four distinct antenna elements borders asame central portion (e.g., central portion 2574, FIG. 25H) of thenear-field antenna, and a second end portion of the respectivemeandering pattern followed by each of the four distinct antennaelements borders a distinct edge (e.g., one of the edges 2572, FIG. 25H)of the near-field antenna. Further, a longest dimension of therespective meandering pattern followed by each of the four distinctantenna elements may be closer to the distinct edge of the near-fieldantenna than to the same central portion of the near-field antenna. Inaddition, a shortest dimension of the respective meandering patternfollowed by each of the four distinct antenna elements may be closer tothe same central portion of the near-field antenna than the distinctedge of the near-field antenna.

In some embodiments, the four distinct coplanar antenna elements areformed on or within a substrate. For example, as shown in FIGS. 25A and25B, opposing first and second surfaces of the four distinct coplanarantenna elements are exposed and coplanar with opposing first and secondsurfaces of the substrate 2506. It is noted that a dielectric (e.g.,thermoplastic or thermosetting polymer) can be deposited over the fourdistinct coplanar antenna elements so that the antenna elements areprotected (may or may not be visible depending on the properties of thedielectric). In some embodiments, the substrate may include ametamaterial of a predetermined magnetic permeability or electricalpermittivity. The metamaterial substrate can increase the performance ofthe near-field antenna as a whole (e.g., increase radiation efficientwhen compared to a substrate made from a common dielectric).

The near-field antenna further includes switch circuitry (e.g., switch2630, FIG. 26) coupled to at least two of the four coplanar antennaelements. For example, the near-field antenna may include a first feed(e.g., feed 2508-A) with opposing first and second ends, where the firstend of the first feed is connected to a first of the two antennaelements composing the first dipole antenna and the second end of thefirst feed is connected to the switch circuitry, e.g., via metal tracesdeposited on a printed circuit board 2514 (FIG. 25E). In addition, thenear-field antenna may include a second feed (e.g., feed 2508-B) withopposing first and second ends, where the first end of the second feedis connected to a first of the two antenna elements composing the seconddipole antenna and the second end of the second feed is connected to theswitch circuitry, e.g., via metal traces (e.g., busing 208) deposited onthe printed circuit board 2514. The feeds and the printed circuit boardare discussed in further detail above with reference to FIG. 25E.

The near-field antenna also includes a power amplifier (e.g., poweramplifier(s) 108, FIG. 26) coupled to the switch circuitry (e.g., viathe metal traces), and an impedance-adjusting component (e.g., component2520, FIG. 26) coupled to the switch circuitry (e.g., via the metaltraces). The near-field antenna may also include a controller (e.g., RFpower transmitter integrated circuit 160, FIGS. 1A and 26) configured tocontrol operation of the switch circuitry and the power amplifier. Thecontroller may be connected to the switch circuitry and the poweramplifier via the metal traces. The power amplifier, theimpedance-adjusting component, and the controller are discussed infurther detail above with reference to FIG. 26.

The method 3000 further includes instructing (3004) the switch circuitryto couple: (i) the first dipole antenna to the power amplifier, and (ii)the second dipole antenna to the impedance-adjusting component (or viceversa). For example, with reference to FIG. 26, the integrated circuit160 may send the “Control Out” signal to the switch circuitry 2630,which causes one or more first switches in the switch circuitry 2630 toclose and connect a respective power amplifier 108 with the first dipoleantenna 2501-A. The “Control Out” signal also causes one or more secondswitches in the switch circuitry 2630 to close and connect theimpedance-adjusting component 2620 with the second dipole antenna2501-B. It is noted that, in some embodiments, the switch circuitry 2630includes first and second switch circuits. In such embodiments, thefirst switch circuit is closed to connect the first dipole antenna tothe power amplifier and the second dipole antenna to theimpedance-adjusting component. Further, the second switch circuit isclosed to connect the first dipole antenna to the impedance-adjustingcomponent and the second dipole antenna to the power amplifier.Controlling operation of the switch circuitry 2630 is discussed infurther detail above with reference to FIG. 26.

The one or more signals generated and provided by the controller may bebased on information received from a wireless-power-receiving device(e.g., receiver 104, FIG. 2B). For example, the controller may receivelocation information for the wireless-power-receiving device, (ii)polarization information for a power-receiving-antenna of thewireless-power-receiving device, and/or (iii) orientation informationfor the wireless-power-receiving device, each of which may be receivedfrom the wireless-power-receiving device. Further, the one or moreelectrical signals may be based on this received information. Putanother way, the controller may be configured to control operation ofthe switch circuitry and the power amplifier based on one or more of:(i) a location of a wireless-power-receiving device (as indicated by thelocation information), (ii) a polarization of a power-receiving-antennaof the wireless-power-receiving device (as indicated by the polarizationinformation), and (iii) an orientation of the wireless-power-receivingdevice (as indicated by the orientation information).

As explained above with reference to FIG. 26, the switch circuitry isconfigured to switchably couple the first and second dipole antennas2501-A, 2501-B to the impedance-adjusting component 2620 and the poweramplifier 108, respectively (or vice versa), in response to receivingone or more electrical signals from the RF power transmitter integratedcircuit 160 (e.g., the “Control Out” signal). Further, in someembodiments, the switch circuitry may be configured to switchably couplethe first dipole antenna to the power amplifier and the second dipoleantenna to the impedance-adjusting component when the near-field antennais in a first operation mode. Moreover, the switch circuitry may beconfigured to switchably couple the second dipole antenna to the poweramplifier and the first dipole antenna to the impedance-adjustingcomponent when the near-field antenna is in a second operation modedistinct from the first operation mode.

The method 3000 further includes instructing (3006) the power amplifierto feed electromagnetic signals to the first dipole antenna via theswitch circuitry. For example, with reference to FIG. 26, the integratedcircuit 160 sends the “RF Out” signal to the power amplifier. The poweramplifier may, in turn, amplify (if needed) the received “RF Out”signal, and then provide the amplified RF signal to the first dipoleantenna via the switch circuitry. The electromagnetic signals, when fedto the first dipole antenna, cause the first dipole antenna to radiateelectromagnetic signals to be received by the wireless-power-receivingdevice, which is located within a threshold distance from the near-fieldantenna. The wireless-power-receiving device can use energy from theradiated electromagnetic signals, once received, to power or charge anelectronic device coupled with the wireless-power-receiving device.Additionally, because the second dipole antenna is connected to theimpedance-adjusting component and the first dipole antenna is not, animpedance of the second dipole antenna is adjusted (by theimpedance-adjusting component) so that the impedance of the seconddipole antenna differs from an impedance of the first dipole antenna. Insuch an arrangement, the first dipole antenna and the second dipoleantenna are detuned (e.g., an operating frequency of the first dipoleantenna differs from an operating frequency of the second dipoleantenna).

In some embodiments, the method 3000 further includes reflecting, by thereflector, at least a portion of the electromagnetic signals radiated bythe first dipole antenna. In addition, in some embodiments, the method3000 further includes cancelling, by the reflector, at least a portionof the electromagnetic signals radiated by the first dipole antenna.

All of these examples are non-limiting and any number of combinationsand multi-layered structures are possible using the example structuresdescribed above.

Further embodiments also include various subsets of the aboveembodiments including embodiments in FIGS. 1-30 combined or otherwisere-arranged in various embodiments, as one of skill in the art willreadily appreciate while reading this disclosure.

The terminology used in the description of the invention herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe invention and the appended claims, the singular forms “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will also be understood that theterm “and/or” as used herein refers to and encompasses any and allpossible combinations of one or more of the associated listed items. Itwill be further understood that the terms “comprises” and/or“comprising,” when used in this specification, specify the presence ofstated features, steps, operations, elements, and/or components, but donot preclude the presence or addition of one or more other features,steps, operations, elements, components, and/or groups thereof.

It will also be understood that, although the terms “first,” “second,”etc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms are only used todistinguish one element from another. For example, a first region couldbe termed a second region, and, similarly, a second region could betermed a first region, without changing the meaning of the description,so long as all occurrences of the “first region” are renamedconsistently and all occurrences of the “second region” are renamedconsistently. The first region and the second region are both regions,but they are not the same region.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A near-field antenna comprising: a reflector;four distinct coplanar antenna elements, offset from the reflector, eachof the four distinct antenna elements following respective meanderingpatterns, wherein: two antenna elements of the four coplanar antennaelements form a first dipole antenna along a first axis; and another twoantenna elements of the four coplanar antenna elements form a seconddipole antenna along a second axis perpendicular to the first axis; apower amplifier configured to feed electromagnetic signals to at leastone of the first and second dipole antennas; an impedance-adjustingcomponent configured to adjust an impedance of at least one of the firstand second dipole antennas; and switch circuitry coupled to the poweramplifier, the impedance-adjusting component, and the first and seconddipole antennas, the switch circuitry being configured to: (i)switchably couple the first dipole antenna to the power amplifier andthe second dipole antenna to the impedance-adjusting component, or (ii)switchably couple the second dipole antenna to the power amplifier andthe first dipole antenna to the impedance-adjusting component.
 2. Thenear-field antenna of claim 1, wherein: in a first mode of operation forthe near-field antenna, the switch circuitry couples (i) the firstdipole antenna to the power amplifier and (ii) the second dipole antennato the impedance-adjusting component; and in a second mode of operationfor the near-field antenna, the switch circuitry couples (i) the seconddipole antenna to the power amplifier and (ii) the first dipole antennato the impedance-adjusting component.
 3. The near-field antenna of claim2, wherein: in the first mode of operation for the near-field antenna,the first dipole antenna is to receive electromagnetic waves from thepower amplifier and radiate the received electromagnetic waves having afirst polarization; and in the second mode of operation for thenear-field antenna, the second dipole antenna is to receiveelectromagnetic waves from the power amplifier and radiate the receivedelectromagnetic waves having a second polarization different from thefirst polarization.
 4. The near-field antenna of claim 3, wherein awireless-power-receiving device, located within a threshold distancefrom the near-field antenna, is configured to harvest the radiatedelectromagnetic waves and use the harvested electromagnetic waves topower or charge an electronic device coupled with thewireless-power-receiving device.
 5. The near-field antenna of claim 1,further comprising a controller configured to control operation of theswitch circuitry and the power amplifier.
 6. The near-field antenna ofclaim 5, wherein the controller is configured to control operation ofthe switch circuitry and the power amplifier based on one or more of:(i) a location of a wireless-power-receiving device, (ii) a polarizationof a power-receiving-antenna of the wireless-power-receiving device, and(iii) a spatial orientation of the wireless-power-receiving device. 7.The near-field antenna of claim 1, further comprising: a first feedconnected to a first of the two antenna elements of the first dipoleantenna and the switch circuitry, wherein the first feed is configuredto supply electromagnetic signals to the first antenna element of thefirst dipole antenna that originate from the power amplifier when thepower amplifier is switchably coupled to the first dipole antenna by theswitch circuitry; and a second feed connected to a first of the othertwo antenna elements of the second dipole antenna and the switchcircuitry, wherein the second feed is configured to supplyelectromagnetic signals to the first antenna element of the seconddipole antenna that originate from the power amplifier when the poweramplifier is switchably coupled to the second dipole antenna by theswitch circuitry.
 8. The near-field antenna of claim 1, wherein: a firstantenna element of the four distinct coplanar antenna elements is afirst pole of the first dipole antenna; a second antenna element of thefour distinct coplanar antenna elements is a second pole of the firstdipole antenna; a third antenna element of the four distinct coplanarantenna elements is a first pole of the second dipole antenna; and afourth antenna element of the four distinct coplanar antenna elements isa second pole of the second dipole antenna.
 9. The near-field antenna ofclaim 1, wherein: the two antenna elements that form the first dipoleantenna each include two segments that are perpendicular to the firstaxis; and the other two antenna elements that form the second dipoleantenna each include two segments that are parallel to the first axis.10. The near-field antenna of claim 1, wherein: a first end portion ofthe respective meandering pattern followed by each of the four distinctantenna elements borders a same central portion of the near-fieldantenna; a second end portion of the respective meandering patternfollowed by each of the four distinct antenna elements borders adistinct edge of the near-field antenna; and a longest dimension of therespective meandering pattern followed by each of the four distinctantenna elements is closer to the distinct edge of the near-fieldantenna than to the same central portion of the near-field antenna. 11.The near-field antenna of claim 10, wherein a shortest dimension of therespective meandering pattern followed by each of the four distinctantenna elements is closer to the same central portion of the near-fieldantenna than the distinct edge of the near-field antenna.
 12. Thenear-field antenna of claim 1, wherein the reflector is a solid metalsheet of copper or a copper alloy.
 13. The near-field antenna of claim1, wherein the reflector is configured to reflect at least a portion ofthe electromagnetic signals radiated by the first or second dipoleantennas.
 14. The near-field antenna of claim 1, wherein the fourdistinct coplanar antenna elements are formed on or within a substrate.15. The near-field antenna of claim 14, wherein the substrate comprisesa metamaterial of a predetermined magnetic permeability or electricalpermittivity.
 16. The near-field antenna of claim 1, wherein therespective meandering patterns are all the same.
 17. The near-fieldantenna of claim 16, wherein the two antenna elements that form thefirst dipole antenna are aligned along the first axis such that therespective meandering patterns followed by each of the two antennaelements are mirror images of one another.
 18. The near-field antenna ofclaim 17, wherein the other two antenna elements that form the seconddipole antenna are aligned along the second axis such that therespective meandering patterns followed by each of the other two antennaelements are mirror images of one another.
 19. A method of wirelesslycharging a receiver device, the method comprising: providing anear-field antenna that comprises: a reflector; four distinct coplanarantenna elements, offset from the reflector, each of the four distinctantenna elements following respective meandering patterns, wherein: (i)two antenna elements of the four coplanar antenna elements form a firstdipole antenna aligned with a first axis; and (ii) another two antennaelements of the four coplanar antenna elements form a second dipoleantenna aligned with a second axis perpendicular to the first axis;switch circuitry coupled to at least two of the four coplanar antennaelements; a power amplifier coupled to the switch circuitry; and animpedance-adjusting component coupled to the switch circuitry;instructing the switch circuitry to couple: (i) the first dipole antennato the power amplifier, and (ii) the second dipole antenna to theimpedance-adjusting component; instructing the power amplifier to feedelectromagnetic signals to the first dipole antenna via the switchcircuitry, wherein: the electromagnetic signals, when fed to the firstdipole antenna, cause the first dipole antenna to radiateelectromagnetic signals to be received by a wireless-power-receivingdevice located within a threshold distance from the near-field antenna,and an impedance of the second dipole antenna is adjusted by theimpedance-adjusting component so that the impedance of the second dipoleantenna differs from an impedance of the first dipole antenna.
 20. Anon-transitory computer-readable storage medium storing executableinstructions that, when executed by one or more processors of anear-field antenna with a reflector, four distinct coplanar antennaelements, switch circuitry coupled to at least two of the four coplanarantenna elements, a power amplifier coupled to the switch circuitry, andan impedance-adjusting component coupled to the switch circuitry, causethe near-field antenna to: instruct the switch circuitry to couple: (i)the first dipole antenna to the power amplifier, and (ii) the seconddipole antenna to the impedance-adjusting component; instruct the poweramplifier to feed electromagnetic signals to the first dipole antennavia the switch circuitry, wherein: the electromagnetic signals, when fedto the first dipole antenna, cause the first dipole antenna to radiateelectromagnetic signals to be received by a wireless-power-receivingdevice located within a threshold distance from the near-field antenna,and an impedance of the second dipole antenna is adjusted by theimpedance-adjusting component so that the impedance of the second dipoleantenna differs from an impedance of the first dipole antenna.